Abstract: The germicidal efficacies of polyhexamethylene biguanidine hydrochloride and polyhexamethylene guanidine hydrochloride were comparatively studied to Escherichia coli, Staphylococcus aureus, Staphylococcus albus and Pseudomonas aeruginosa by inhibition zone method. The results showed that two kinds of poly guanidine for the above-mentioned four kinds of common pathogenic bacteria have significantly bactericidal capacity, and both have synergistic effect on germicidal efficacy.