Abstract: In order to understand the morphological characteristics of parasporal crystals, the parasporal crystals of 3 Bacillus thuringiensis strains:Bt33、Bt53 and BtHB were extracted with liquid diphasic separation, the separation purity was Bt33 99.9%, Bt53 99.9%, BtHB 99.8%, respectively.Under scanning electron microscope and transmission electron microscope, the findings were that all of 3 strains had rhombic, long oval or irregular crystals, several strains contained square crystals, a few long oval crystals had "trail" or protuberance;different strains had different crystal numbers and shapes.The proportion of rhombic crystal in Bt33 was 75%, that of rectangular and oval crystal was 22%-23%, and the rest was in irregular form.For Bt53, 90% was long oval, 5% was rhombic, and the other 5% was irregular form.For BtHB, 30% was rhombus crystal, 64%-65% was long oval, and 5% was square.The crystal size was differed.