OBJECTIVE: To compare the coagulation function of frozen and fresh platelets in vitro, and investigate the effect of shock storage or cryopreservation on platelet function. STUDY DESIGN: Platelets of healthy people were collected, divided into 2 equal parts, respectively, and subjected to shock storage and cryopreservation. Using 5% DMSO as protective agent, platelets were frozen at -80°C low temperature, then stored for 4 days and cryopreserved for 4 days. The MA value was detected by thromboelastogram, the CD62P value was detected by flow cytometry, and the values were compared. RESULTS: The MA value of frozen platelet thromboelastogram (30.80±6.27 mm) was greater than that of fresh platelets (28.94±5.82 mm), indicating that the coagulation function of frozen platelets in vitro was stronger than that of fresh platelets, while the CD62P content of frozen platelets (29.50±3.06%) was smaller than that of fresh platelets (55.25±4.09%), indicating that the aggregation function of frozen platelets was stronger than that of fresh platelets. CONCLUSION: Frozen platelets have stronger coagulation function than fresh platelets in vitro. Platelets are stored for a long time after freezing to meet the increasing clinical demand for platelets. (Anal Quant Cytopathol Histpathol 2021;43:866-872) © Science Printers and Publishers, Inc. © 2021 Science Printers and Publishers Inc.. All rights reserved.