Objective  To investigate the inhibitory mechanism of plasmin on the formation of posterior capsule opacity （PCO）. Methods  In an experimental study， twenty 4-month-old New Zealand white rabbits were selected （approximate weight 2.0 to 2.5 kg）. No eye-related pathological defects were observed in any rabbits. They were randomly divided into two groups of 10 rabbits each： a control group and an experimental group. All rabbits underwent phacoemulsification surgery under general anesthesia. At the conclusion of the surgery， rabbits in the experimental group were injected with plasmin 1 IU （0.2 ml） in the anterior chamber and the control group was injected with saline 0.2 ml. Inflammation in the anterior chamber and the mobidity of PCO were recorded over a period of time. Basic fibroblast growth factor （bFGF） was measured by the ELISA method for each group. In addition， a semi-quantitative analysis of lens proliferating cell nuclear antigen （PCNA） was performed by immunohistochemical staining using a computer assisted image analysis system. All data were analyzed by the SPSS 13.0 statistical software program （P<0.05 was considered as a significant difference）. Results  ①Inflammation of the anterior chamber （AC）. On the first day after surgery， all rabbit eyes in the two groups presented with variable inflammation of the AC. After 3 days， reaction in the AC was reduced and the morbidity of the inflammation was significantly decreased in the experimental group compared to the control group at 3 days and 7 days （χ2=4.33， P<0.05； χ2=7.06， P<0.01）.②Morbidity of PCO. The morbidity of the PCO was 45% in the experimental group and 90% in the control group at 60 days. The decrease was significant compared to the control group （χ2=6.14， P<0.05）. ③Concentration of basic fibroblast growth factor （bFGF）. ELISA analysis demonstrated that the concentration of bFGF in the experimental group was significantly decreased compared to the control group at all time points from one day to 4 weeks. And there was no significant difference between two groups at 60 days. ④Optical density. There was a single laminar layer of cells in the experimental group and mutiple layers of laminar cells in the control group based on the semi-quantitative analysis of immunohistochemical staining. There was a significant difference in optical density（OD） between the experimental and control groups. Conclusion  ①The use of plasmin is an effective method for controlling inflammation in the AC after phaco surgery. ②Plasmin significantly down regulates the concentration of bFGF in AC. ③Plasmin can decrease the morbidity of PCO and slow its development.