TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: In cultivating biologic strain for purifying mixed organic waste gas, the step of cultivating strain comprises: (a) preparing liquid culture medium of strain one: taking phosphate buffer solution, Magnesium sulfate (MgSO4) solution, calcium chloride (CaCl2) solution, ferric chloride (FeCl3) solution and microelement solution to mix, adding distilled water to dilute, and regulating pH value, sterilizing through high pressure steam, after packing aseptically, adding liquid xylene and diesel oil as only carbon source and energy, sealing and storing; (b) acclimatizing: aerating and activating the active sludge mixed solution from the dyeing wastewater treatment plant adequately, and then treating with ultrasonator to disperse the sludge floccule evenly, taking the treated sludge mixed solution into screened and acclimatized culture medium, oscillating and cultivating aerobically the micro-organism by using shaking bed test; and (c) inoculating the screened strain into activated and enriched culture medium, after oscillating aerobically, placing into a high-speed centrifuge to centrifuge, and then cleaning with phosphate buffer solution, centrifuging, preparing the centrifuged strain into strain suspension solution, obtaining the strain one. The liquid culture medium of the strain one comprises components as follows: phosphate buffer solution: 20-25 g/L of dipotassium phosphate monohydrate (K2HPO4.H2O), 6-9 g/L of Potassium dihydrogen phosphate (KH2PO4), 30-35 g/L of disodium hydrogen phosphate dodecahydrate (Na2HPO4asterisk12H2O) and 3-6 g/L of ammonium chloride (NH4Cl); MgSO4 solution: 20-25 g/L of MgSO4; CaCl2 solution: 35-40 g/L of CaCl2; FeCl3 solution: 0.1-0.3 g/L of FeCl3; microelement solution: 35-40 mg/L of manganese sulfate monohydrate (MnSO4asteriskH2O), and 40-45 mg/L of Zinc sulfate Monohydrate (ZnSO4asteriskH2O). The liquid culture medium of the strain one comprises optimal components as follows: phosphate buffer solution: 22.0 g/L of K2HPO4asteriskH2O, 7.6 g/L of KH2PO4, 31.8 g/L of Na2HPO4asterisk12H2O and 4.0 g/L of NH4Cl; MgSO4 solution: 22.0 g/L of MgSO4; CaCl2 solution: 36.0 g/L of CaCl2; FeCl3 solution: 0.15 g/L of FeCl3; microelement solution: 37.0 mg/L of MnSO4asteriskH2O, and 41.0 mg/L of ZnSO4asteriskH2O. The activated and enriched culture medium comprises components as follows: 5.0 g of beef extract, 10 g of peptone, 5 g of sodium chloride (NaCl) and 1000 mL of water; the culture medium is sterilized at high pressure. The culture medium of inoculums for acclimatizing inoculums of strain one and strain two comprises components as follows: 0.0-1.0 g/L of hydrolysis starch, 0.5-1 g/L of urea, 0.2-0.3 g/L of KH2PO4, 0.2-0.3 g/L of Na2HPO4, 0.1-0.2 g/L of MgSO4asterisk7H2O, 0.02-0.03 g/L of CaCl2 and 0.05-0.15 g/L of vitamin B1. The volume ratio of strain two to strain one is 20:1. The culture medium of inoculums for acclimatizing inoculums of strain one and strain two comprises optimal components as follows: 1.0 g/L of hydrolysis starch, 1.0 g/L of urea, 0.25 g/L of KH2PO4, 0.25 g/L of Na2HPO4, 0.15 g/L of MgSO4asterisk7H2O, 0.025 g/L of CaCl2 and 0.01 g/L of vitamin B1. It comprises: in early time of cultivating and acclimatizing the inoculums, taking culture medium of hydrolysis starch having a concentration of 1.0 g/L as single carbon source and energy, and adding N, P, Mg, Ca and Fe Nutrient elements. It comprises after finishing cultivating and acclimatizing early time, reducing the starch usage in the culture medium gradually, increasing waste gas amount; stopping inletting gas and oscillating every 48 hours, standing and depositing for 2-3 hours, removing the supernatant, and adding culture medium of inoculums.