NOVELTY - A separation, purification and domestication method of Bacillus thuringiensis comprises adding water into sludge purification tank for liquid waste for producing pesticide oxadiazon, standing, taking 1 mL of supernatant liquor, serially diluting 10-1-10-8 by 0.8% of physiological saline to obtain 8 pts.wt. of diluted bacterium liquid; on aseptic platform, injecting 15-20 mL of beef extract peptone solid medium; spreading 0.1-0.2 mL of diluted bacterium liquid in 8 plates; incubating; and inoculating the bacterial strain after purified into inorganic salt medium.    USE - Method of separating, purifying and domesticating Bacillus thuringiensis, i.e. Bacillus thuringiensis ODPY used for treating organic wastewater and high salinity organic wastewater, for producing organic wastewater by pesticide oxadiazon, and for biochemically treating persistent organic pollutant wastewater containing aromatic compound such as chloroform and methylbenzene (claimed).    DETAILED DESCRIPTION - A separation, purification and domestication method of Bacillus thuringiensis comprises:    (A) under aseptic condition, adding water into sludge purification tank for liquid waste for producing pesticide oxadiazon, uniformly mixing and standing for 0.5-2 hours, taking 1 mL of supernatant liquor, serially diluting 10-1-10-8 by 0.8% of physiological saline to obtain 8 pts.wt. of diluted bacterium liquid;    (B) on the aseptic platform, taking 8 flats, injecting 15-20 mL of beef extract peptone solid medium after melted and the temperature is lowered to 40-50 degrees C, into each plate, waiting solidification;    (C) taking 0.1-0.2 mL of diluted bacterium liquid in A, uniformly spreading in 8 plates by use of sterilized triangle coating, and numbering in sequence;    (D) placing the prepared 8 plates in the incubator for 18-60 hours at 30 degrees C;    (E) selecting individual bacterial colonies with clear form from each plate, placing on the solidified beef extract peptone solid medium on the other 8 plates according to the numbers, and lining, then placing the plates after lined in the incubator for 18-60 hours at 30 degrees C; repeating the process at least twice; and    (F) inoculating the bacterial strain after purified into the inorganic salt medium as the 5-10% of inoculating amount, 100 mg/l of maximum density, domestication calculating in table flotation with 120-170 rpm at 25-35 degrees C, inoculating into new medium as the 5-10% of inoculating amount each 5-10 days, where the domestication time is not less than 2 month.