Abstract: Six new Bt strains, W14, ZY1, 3346, TMQ2, B31 and P91, were isolated from different habitats by NaAc-antibiotics method. Small- rhomboidal crystals were observed under microscope. SDS-PAGE showed that the molecular weights of the six new Bt strains were all about 130kDa. However, the contents of ICPs were only 0.2% to 0.29%. In addition, none of ICPs was found in B31. Bioassay results showed that the strains had low activities to Cotton Bollworm. We suggested that different sources and habitats infect the Bt ICPs contents and activities to target insects.