The present study analyses the insecticidal crystal proteins (ICPs) from Bacillus thuringiensis strain 4.0718 through two-dimensional electrophoresis and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). By comparing and optimizing the composition of lysis solution, the volume of sample loading and the protocol for isoelectric focusing, a well-focused 2-DE map with high resolution and reproducibility was achieved for the first time. And after an tryptic enzymolisis and a test of part of protein spots by means of MALDI-TOF-MS, the peptides mass fingerprint (PMF) was obtained and, by referring to Swiss-Prot, Cry1Ac and Cry2Aa contained in Bt 4.0718 were identified, with their molecular weights 134160 Da and 71097 Da respectively.