Objective To observe the effects of Huatan Tongluo on the Bederson's scores , the permeability of blood-brain barrier and ultrastructure of hippocampus endothelial cells after thrombolysis in acute cerebral infarction. To provide experimental evidence for the prevention of bleeding after thrombolysis in acute cerebral infarction with Huatan Tongluo. Methods 120 SD male rats were randomly divided into sham group, model group, rt-PA group, Huatan Tongluo combined rt-PA low-dose group, Huatan Tongluo combined rt-PA medium-dose group and Huatan Tongluo combined rt-PA high-dose group(each group was divided in 6h, 24h, 3d, 7d four-phase). MCAO rats were prepared by self-embolus method. rt-PA group and Huatan Tongluo combined rt-PA groups were given rt-PA through tail vein injection and three doses of Huatan Tongluo to treat.To observe the Bederson's scores in rat on four-phase.To detect the permeability of blood-brain barrier(BBB) by the Evans Blue dye (EB dye) and watch the ultrastructure of hippocampus endothelial cells in ischemic region by electron microscopy. Results 1.Bederson's scores: Compared with model group, rt-PA group, Huatan Tongluo combined rt-PA low-dose group, Huatan Tongluo combined rt-PA medium-dose group and Huatan Tongluo combined rt-PA high-dose group significantly lower(P<0.01); Compared with rt-PA group, Huatan Tongluo combined rt-PA medium-dose groups and high-dose groups was significantly lower(P<0.05).2. EB dye: Compared with model group, rt-PA group, Huatan Tongluo combined rt-PA low-dose group, Huatan Tongluo combined rt-PA medium-dose group and Huatan Tongluo combined rt-PA high-dose group(P<0.01); Compared with rt-PA group(6h : (236.72±79.79)ng/g; 24h: (229.72±22.18)ng/g; 3d: (163.34±24.45)ng/g; 7d: (133.21±25.09)ng/g), Huatan Tongluo combined rt-PA medium-dose groups (6h: (121.63±33.27)ng/g; 24h: (153.78±60.67)ng/g; 3d: (76.05±27.11) ng/g; 7d: (72.97±25.81)ng/g)and high-dose groups (6h: (123.11±23.65)ng/g; 24h: (138.36±52.36)ng/g; 3d: (83.00±32.00)ng/g; 7d: (75.06±13.97)ng/g)was significantly lower(P<0.01).3. Electron microscopy: Compared with model group, treatment groups all protected the endothelial cells.In 24h, the Huatan Tongluo combined rt-PA high-dose group was best.At 3d and 7d, the Huatan Tongluo combined rt-PA medium-dose group was best. Conclusion Huatan Tongluo combined rt-PA to thrombolysis can protect the blood-brain barrier and endothelial cells of hippocampal's ischemic region. After thrombolytic, to adjust the medicine drug concentration at different time can play a better treatment results. Key words: Huatan Tongluo; Infarction; Thrombolysis; Blood-brain barrier; Endothelial cells; Morphology