ObjectiveTo establish the ARDS animal model in rats. MethodKM mice and SD rats were divided into control group and paraquat -exposed groups (with a single dose of 100mg/kg in mouse and 120mg/kg in rat). Each group was subdivided into three smaller groups (24 -hour group, 48 -hour group, and 72 -hour group). Blood was collected from the femoral artery of mouse for blood gases analysis. Tissues from lung of rats were embedded in paraffin for histological analysis. Result1.After the paraquat was given, respiration movements of the animals were getting more and more difficult with cough, pink excretions in nasal cavity, progressively decreased appetite, and weight loss. 2.Lung changed from pink color to hepatization in gross view. 3.By blood gases analysis, the blood PH value and PaO 2 gradually decreased, while PaCO 2 and pulmonary coefficient went in the other way. Statistical analysis (t -test) showed an obvious difference between experimental groups and control group ( P <0 .01). 4.Histological section showed a typical inflammation. Transparent membrane formed in the pulmonary alveoli. ConclusionARDS animal model can be successfully produced by means of exposure to paraquat.