Abstract: The properties of nucleic acids of three Bacillus thuringiensis phages with similar morphology from CGVCC and their digested characteristics by restriction endonuclease were compared Nucleic acid of all of 3 phages were linear by molecular spreading after treatment of formamide cytochrome C, and were double strand by thermal denaturetion and electrophoresis of enzyme S_l DNAs of all 3 phages were not sensitive to restriction endonuclease HindⅢ and BamHⅠ,but were digested by EcoRⅠ and HpaⅡ into 8 and 7 fragments respectively The molecular weights of the phages' DNAs were about 48.08kb.