Bacillus thuringiensis insecticidal crystal protein has exhibited high toxicity to some agricultural insects. Cry1Ac insecticidal crystal proteins were firstly obtained from the Bt kurstaki HD73 in the form of parasporal crystals, the open reading frame of the cry1Ac gene contains 3 534 bp encoding a 133 kD protein with 1 178 amino acids and its IE point was 4.84. This paper summarizes the structure, function and gene taxonomy of Cry1Ac insecticidal crystal proteins and reviews as well the research of genetic engineering of insecticidal crystal proteins of Bacillus thuringiensis and its application in transgenic plant breeding. We also analyzed the problems existed in the transgenic plants and molecular plant breeding at present, gave advices on these problems and proposed some new views about utilization of the Bt insecticidal crystal protein with reasons.