Abstract： Objective Using real-time fluorescence quantitative PCR to detect the gene expression of MMP-2,T1MP-1 in the rats' lung intoxicated by paraquat, and to discuss the effect of the MMP-2,T1MP-1 in the acute lung injury and pulmonary fibrosis afltr paraquat intoxication. Method Eighty Sprague-Dawley rats were randomly divided into control group and the intoxication group. The rats of the control group were given equivalent volume of normal saline, and the rats of the intoxication group were given a intraperitoneal injection of paraquat(18 mg/kg) . At 1,3,5,7,14 and 28 days after intoxication, the pathological changes were observed under the light microscope and the expression of MMP-2, TTMP-1 mRNA in the rats lung were detected by using real-time fluorescence quantitative PCR. Results Compared with the control group, in the early days after intoxication, the lung tissue of the intoxication group showed obvious inflammation, pulmonary edema and bleeding. Five daye after intoxication, pulmonary fibrosis could be ideatified and the fibrosis became obvious. At 28 days later the expression of MMP-2 mRNA was remarkably increased in lung tissue from the day of intoxication, and reached the peak 7 days later, It was control group, that in and then gradually, declined however, higher than that in control group (P < 0.01). The expression of TIMP-1 mRNA in lung tissue was also higher than the control group on the day 1, then increased gradually, reached the peak on day 14,7.28 times more than the control group, decreased from the fourteenth day,higher than the control group on day 28 (P < 0.01) . Conclusions MMP-2,TIMP-1 played a very important role in the acute lung injury induced by paraquat, meanwhile the development of pulmonary fibrosis had great relations on their disproportion.