By the temperature-antibiotic method, the author isolated 74 strains Bacillus thuringiensis from totally 764 soil samples which were collected from different altitude Damaoshan mountains of Hebei province. The results showed the optimal collecting area at an altitude of 900 to 1200 m. Light microscope observation showed that the crystals of these Bt strains were in shape of spherical, bipyramidal, square, irregular and so on; 7 kinds of cry gene were found by PCR-RFLP system, and 11 Bt strains harbour unkno...