Objective To compare the levels of platelet parameters and blood coagulation indices across different stages of pregnancy and between preeclampsia (PE) and normal twin pregnant women, and explore the values of these indicators with respect to predication and clinical management of PE . Methods A total of 370 twin pregnancies who gave birth in Peking University Third Hospital from January 2014 to June 2017 were included in this study, including 55 diagnosed as mild PE, 75 as severe PE, and 240 as normal twin pregnancy. Their platelet parameters including platelet count (PLT), platelet distribution width (PDW), mean platelet volume (MPV), and plateletcrit (PCT), and blood coagulation indices including thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen(FIB), and D-dimer (DD) were extracted from medical records, and differences in these indicators among the three groups at different stages of pregnancy were examined. Results ① In all the three groups of patients, the PT decreased and DD increased in the middle and late stage of pregnancy compared to the early stage (P<0.05). In the late pregnancy, the FIB was lower and TT was higher in severe PE group than the other two groups; the DD and APTT in the two PE groups were higher than those in the normal group (P<0.05). ② The PLT and PCT decreased and MPV and PDW increased in the middle and late stage of pregnancy compared to early pregnancy (P<0.05). In the late pregnancy, the PDW and MPV in the two PE groups were higher than those in the normal group (P<0.05), whereas the PLT and PCT in the severe PE group were lower than the normal group (P<0.05). ③ Among these indicators, the area under the curve (AUC) of the receiver-operating characteristic (ROC) curves were relatively higher for TT and PDW in the late pregnancy (67.5% and 70.7%, respectively), indicating good predictive performance of these two indicators for PE; the suggested cut-off value for TT was 13.5 s and for PDW was 13.5 fL. Conclusion ① PE may be associated with abnormal coagulation in both internal and external clotting system and with severe hypercoagulable state of the blood. Dynamic monitoring of the changes of platelet parameters and blood coagulation indices may be helpful in guiding clinical management of PE. ② TT and PDW are two potential indicators for early prediction of PE; it warrants close monitoring of occurrence of PE when the levels of these two indicators exceed the suggested cut-off value at middle and late pregnancy.