Objective To assess the health status of rodent laboratory animals by pathological diagnosis, our lab has being take apart in investigating the quality of laboratory animals in Beijing area for years and offer some advices for standardized breeding to ensure accurate results of scientific research. This paper focuses on the analysis of laboratory rodent samples that collected in October 2014. Methods We collected the heart, liver, spleen, lung, kidney, large intestine and small intestine, and put these organs into 10%Calcium formaldehyde solution for fixation, and then prepared into two different sections for optical microscopy observation including all paraffin specimens stained with H&E and the frozen sections stained with Oil Red-O and PAS. Results The vast majority of laboratory rodents were up to standard, but there still a problem in individual units. The main problem is liver and lung disease. The rate of Hepatocyte swellingis 6% (mouse), 2.5% (rat), 8.2% (guinea pig), moreover part of them were lipidosis, according to Oil Red-O stain. the mainly problem of lung is congestion, edema and Interstitial pneumonia, the detectable rate of pulmonarydiseases is 15.5%(guinea pig). Conclusions The vast majority of laboratory rodents were pathologically diagnosed as healthy animals.The liver disease may be caused by improper feeding.And disease of lung may led by haze, unqualified bedding and low temperature.