NOVELTY - Separating and purifying pure strain capable of aerobically degrading polycyclic aromatic hydrocarbon comprises: (a) mixing basic culture medium, trace metal liquid and vitamin c; (b) adding liquid culture medium; (c) adding polycyclic aromatic hydrocarbon acetone solution; (d) cleaning the absorbent; (e) selecting the flora in the culture container in the super-clean working platform; and (f) treating the operation as one separation and purification cycle.    USE - The method and pure strain are useful for separating and purifying pure strain capable of aerobically degrading polycyclic aromatic hydrocarbon, aerobic degradation experiment of naphthaline, phenanthrene, and fluorine in aerobic condition (all claimed), and biologically degrading and processing polluted soil and water.    ADVANTAGE - The method can obtain pure biological strain capable of aerobically degrading polycyclic aromatic hydrocarbon via separation and purification.    DETAILED DESCRIPTION - Separating and purifying pure strain capable of aerobically degrading polycyclic aromatic hydrocarbon comprises: (a) adding 400 mL of basic culture medium, 1.0 mL of trace metal liquid and 0.1 mL of vitamin c solution into a tapered bottle with the volume of 500 mL, uniformly shaking and using it as liquid culture medium for use, where the preparation of the basic culture medium being as follows: 1.5 g/L of ammonium chloride (NH4Cl), 1.5 g/L of potassium dihydrogen phosphate (KH2PO4) and 0.25 g/L of magnesium chloride (MgCl2), 0.1 g/L of calcium chloride dihydrate (CaCl2.2H2O); preparation of the trace metal liquid being as follows: 50 mg/L of cobalt chloride hexahydrate (CoCl2.6H2O), 0.30 mg/L of copper chloride (CuCl2), 10.0 mg/L of boric acid (H3BO3), 40 mg/L of manganese chloride tetrahydrate (MnCl2.4H2O), 5.0 mg/L of Sodium molybdate dihydrate (Na2MoO4.2H2O), nickel chloride dehydrate (NiCl2.2H2O) and 3.5 mg/L of zinc chloride (ZnCl2); (b) adding 50 mL of liquid culture medium prepared according to step (a) and 0.60 g of agar agar into a tapered bottle with the volume of 150 mL, sterilizing in a high pressure boiler for 20 min at the temperature of 121 degrees C, cooling to 65-70 degrees C in the condition of room temperature, pouring into a culture container with the volume of 160 mL in a super-clean working platform, putting the culture container in the super-clean working platform for 2 days in order to remove the surplus water on surface of the culture medium; (c) adding 0.5 mL of polycyclic aromatic hydrocarbon acetone solution with the concentration of 1 g/L into the culture container of step (b) in the super-clean working platform, in reciprocating inclined rotating the culture container to make the polycyclic aromatic hydrocarbon acetone solution uniformly distributed, putting the culture container in the super-clean working platform for 2 days in order to remove the acetone on surface of the culture medium; (d) adding 10 mL of liquid medium prepared in step (a) and 0.25 g of agar agar into a tapered bottle with the volume of 25 mL, sterilizing in a high pressure boiler for 20 min at the temperature of 121 degrees C, cooling to 38-40 degrees C in the super-clean working platform; (e) adding 1 mL of polycyclic aromatic hydrocarbon aerobic degrading flora solution obtained via enrichment and domestication into the tapered bottle of step (d) in the super-clean working platform, uniformly shaking and absorbing 1 mL and slowly adding into the culture container of step (c), in reciprocating inclined rotating the culture container to make the culture medium solution inoculated with mixed flora uniformly distributed, putting the culture container into a culture cabinet at the temperature of 25 degrees C, observing for 10-15 days to find the obvious flora; (f) adding 4.0 mL of polycyclic aromatic hydrocarbon acetone solution with the concentration of 1 g/L into the tapered bottle with the volume of 25 mL in the super-clean working platform, opening the tapered bottle and placing for 2 days in order to acetone; (g) cleaning the absorbent for 5 times by using deionized water at the ratio between the water and the high molecular resin of 5:1 by mass, then cleaning the absorbent for 3 times by using 99% of ethanol at the ratio between ethanol and absorbent of 3:1 by mass, putting the cleaned absorbent into the super-clean working platform for 2 days in order to completely remove ethanol in the absorbent; (h) adding 10 mL of liquid culture medium prepared in step (a) into the tapered bottle of step (f), adding 0.15 g of absorbent processed by step (g), sealing and putting into an oscillator at the rotating speed of 100 rpm to be balanced for 2 days; (i) selecting the flora in the culture container in the super-clean working platform, inoculating it into the tapered bottle of step (h), culturing in the oscillator at the rotating speed of 100 rpm for 5-7 days at the temperature of 25-30 degrees C; and (j) treating the operation from step (b) to step (i) as one separation and purification cycle, repeating from the step (b) to step (i), using the strain liquid of step (i) used in the former separation and purification cycle to replace the polycyclic aromatic hydrocarbon aerobic degrading flora solution used in step (e), separating and purifying for more than 8 cycles, obtaining the pure strain capable of aerobically degrading polycyclic aromatic hydrocarbon with high efficiency. INDEPENDENT CLAIMS are:    (1) use of the pure strain capable of aerobically degrading polycyclic aromatic hydrocarbon for aerobic degradation experiment of naphthaline in aerobic condition, it is proved by result that the separated pure strain can well aerobically degrading naphthaline; when initial concentration of naphthaline is 26.1 mg/L, it can be degraded to be less than 0.02 mg/L after two days; for aerobic degradation experiment of phenanthrene in aerobic condition, it is proved by result that the separated pure strain can well aerobically degrading phenanthrene; when initial concentration of phenanthrene is 1.05 mg/L, it can be degraded to be less than 0.01 mg/L after two days, and for aerobic degradation experiment of fluorine in aerobic condition, it is proved by result that the separated pure strain can well aerobically degrading fluorine; when initial concentration of fluorine is 0.11 mg/L, it can be degraded to be less than 0.01 mg/L after one day; and    (2) an aerobic degradation experiment of pyrene in aerobic condition comprising using the separated and purified strain of the invention, where it is proved by result that the separated pure strain can well aerobically degrading pyrene; when initial concentration of pyrene is 0.10 mg/L, it can be degraded to be less than 0.01 mg/L after one day.