Objective To observe the injury of some chief organ induced by paraquat (PQ) poisoning in rats, and to explore the mechanism. Method A total of 60 inbred line SD rats were randomly divided into experimental group (n = 30) and control group (n = 30), and each group was further divided into 6 subgroups (n =5) as per the sacrifice of rats at different intervals. The rats of experimental group received the intra-abdominal injection of paraquat (1 mg/mL, 18 mg/kg), and the rats of control group were treated with the same amount of saline solution instead. The rats of each subgroup were sacrificed separately 2 h,6 h, 12 h,24 h,72 h and 120 h after administration of PQ or saline. Lungs, livers and kidneys were taken for histopathological study. Results There was noticeable exudate in lung tissue of rats in experimental group in the early stage. And then the cystic changes in the liver of rats in experimental group were found. A noticeable hemoglobin was found in the renal tubules 24 h after modeling. But the exudation in lung decreased 24 h later, and in the mean time, the disorganization of pulmonary alveoli was obvious and some remarkable collagen appeared in the interstitial tissue of lung, and it was significantly obvious 72 h after modeling. In the liver of rats in experimental group, the injured tissue had some extent of repair in 72 h after modeling, and recovered gradually. But the injury of kidney was exacerbated 72 h after modeling. In the control group, the lung, liver and kidney were not changed in all stages after modeling.Conclusions The paraquat could induce failure of some chief organs in SD rats. The injury was most remarkable in the lung in a progressive way. The kidney injury was not more severe than that of lung tissue, but the pathological changes of the kidney became worse and worse as time taken. The injury of liver induced by paraquat was slight, and the injury could heal up gradually.