Abstract: The fibrinogenase of T.mucrosquamatus venom (TMVFg) could hydrolyze the tripeptide Bz-Phe-Val-Arg-PNA,but it showed low enzymatic activity toward Cbz-Gly-Pro-Arg-PNA which was a good substrate of thrombin.TMVFg apparently prolonged plasma thrombin time,plasma recalcification time and fibrinogen solution thrombin time.By using MonoQ ion-exchange chromatography (EPLC),fibrinogen products degraded with TMVFg were isolated.One,designated as FDP Ⅰ,inhibited fibrin clot formation,Another one,designated as FDP Ⅱ,not only enhanced the fibrin clot but also inhibited platelet aggregation induced by TMVA (a platelet aggregation inducer isolated from the venom of T.mucrosquamatus) and this inhibitory effect was dose dependent.FDP Ⅱ had no effect on platelet aggregation induced by ADP or by arachidonic acid (AA).The results also showed that TMVFg had certain inhibitory effect on thrombin activities.