Cadherin is one of the most important receptors for crystal toxins of Bacillus thuringiensis in insects. The type, structure and distribution of cadherin in insects are sketched. The binding sites of both crystal toxin and cadherin are discussed in depth. The mechanism of interaction of cadherin with crystal toxin of Bacillus thuringiensis is expounded in detail, and the relations betweeen cadherin and insect resisitance are also presented.