Objective：To investigate the physiologic characteristics of coagulation parameters during normal pregnancy and puerperium.Methods：One hundred and sixty normal pregnant women were involved in a serial random study to measure prothrombin time（PT），activated partial thromboplastin time（APTT）, thrombin time（TT）, fibrinogen（Fbg）. Blood samples were collected in 10 th-14 th, 20 th-24 th and 30 th-34 th gestational weeks and on the third day of puerperium respectively, The same measurements were also performed on 50 non-pregnant women. Results：PT，APTT and TT were shortened in pregnant women compared with non-pregnant controls. Fbg concentration was always increased in pregrant women versus non-pegnant controls in an increaseng trend with the increase of gestational time. The most significant variations for APTT were recorded up to the 20 th week. From the 20 th week onwards, APTT level remained stable until after the delivery. The level of PT in the mid stage was lower than that in other stages, and there was statistical differences between the perinatal periods. No statistical difference in TT between the different gestational weeks were observed, but the puerperium was significant longer than the gestational period. Fbg level was increased with the increase of gestational time. Conclusion：ＰT, APTT, TT, Fbg show great variation during pregnancy, and they appear to play a major role in finding the abnormal changes of the pregnant women early.