Objective. To study the effects of Yiqi Huoxue (YQHX) granules on platelet activation and aggregation induced by thrombin. Methods. The effect of YQHX on platelet aggregation rate was detected by platelet aggregation instrument; the effect of YQHX on thrombosis time was observed by the mouse mesentery thrombosis model. DAMI cells were induced to transform into platelet-like granules using PMA, and the effects of SCH (PAR-1 inhibitor) on thrombin-induced changes in platelet intracellular calcium concentration, PAR-1 protein expression, and phosphorylation of MAPK were examined. Results. Compared with the control group, the platelet aggregation rate, PAR-1 protein expression, phosphorylation of ERK1/2, and p38 protein in the YQHX group decreased (
P
<
0.05
), and there was no significant difference between the YQHX + SCH group and YQHX group (
P
>
0.05
). Conclusion. YQHX suppresses the platelet activation induced by thrombin by inhibiting PAR-1 expression.