Through the validation of methodology, the microbial limit test method of roxithromyin and azithromycin was established. Refer to “Chinese Pharmacopoeia” 2010 edition of microbial limit test, microbial limit test validation was conducted by using the membrane filtration method.  The results show that low speed centrifugalization combined with membrane filtration method is adopted for bacterial count, plate method is adopted for mycete and saccharomycete count, and membrane filtration method is adopted to eliminate the antimicrobial effect of control-bacteria.