Abstract:Objective To survey the infectious rate and strain of M.pulmonis in the rodent laboratory animal in Lanzhou districton. Methods The M.pulmonis infection of 640 rodents labovatory animals in Lanzhou were surveyed by culture method. The isolates were cloned and identified by morphology, biochemical features and serology. Resultsd and conclusion The infectious rate of M.pulmonis was 23 % in the conventional mice.No infection were fond in rat, guinea pig and hamster. There was no seasonal correlation to M.pulmonis infection in the mice. According to theose experiments, the isolates were Mycoplarma pulmonis, Mycoplasmataceac, Mycoplasmatales.