Abstract: Objective To explore the effects of atorvastatin on lung injury induced by paraquat and on matrix metalloproteinases (MMPs) and their inhibitors(TIMPs). Methods A total of 45 male Wister rats were randomly divided into control group, PQ treated group,and atorvastatin treatment group(15 in each group).The rats in the PQ group and the treatment group were given paraquat 50 mg/kg orally; the rats in the treatment group received atorvastat in 20 mg/kg. the animals were dissected in batches (on the 7th, 14th and 28th day)and related samples were collected. The pathology of lung tissue was studied.The levels of MMP-9 and TIMP-1 in the lung tissue were measured by immunohistochemistry, RT-PCR and Western-blot. The levels of MMP-9 and TIMP-1 in fibrocyte were detected by RT-PCR. The levels of MMP-9 and TIMP-1 in Serum were detected by ELISA. Results Lung injury was obvious in PQ treated group, while it was less serious in the atorvastatin treatment group. The expression level of MMP-9 and TIMP-1 were higher in the atorvastatin treatment compared with that of the control group, but lower than that in PQ treated group. The serum MMP-9 level was the highest in the alveoli inframammary stage (day 7), and declined with time (day 14 and 28), while all were higher than that in atorvastatin treatment group. In the same phase, there were no significant difference of serum TIMP-1 level among the three groups(P>0.05). The expression levels of MMP-9 and TIMP-1 of lung fibroblasts in atorvastatin treatment group were lower compared with those of PQ treated group and higher than those in control group. Conclusion Atorvastatin could alleviate lung injury induced by PQ in rats by preventing the secretion of MMP-9 in the lung while has no effect on the serum level of MMP-9 and TIMP-1.