Abstract: The model of arterial thrombosis induced by FeCl₃ in rat was used to investigate the antithrombotic effect of pGlu-Asn-Trp（pENW）.Platelet aggregation was tested according to Born’s methods.Platelet cytosolic calcium was determined using of Fura-2/AM.Prothrombin time (PT)，thrombin time (TT) and activated partial thromboplastin time (APTT) were tested for exploring the effect of pENW on prothrombin.pENW (iv) inhibited arterial thrombosis induced by FeCl₃ and platelet aggregation induced by ADP,respectively (P<0.05).Ex vivo pENW markedly lowered the cytosolic calcium higher concentration induced by ADP in platelet.However，there was no significant effect on PT，TT and APTT.These results showed that pENW evidently inhibited platelet aggregation and decreased the concentration of platelet cytosolic calcium.Results suggest that the antithrombotic effect of pENW may be related to its anti-platelet aggregation and the decrease of platelet cytosolic calcium.