Abstract: Objective This study is to explore whether the parameter modification can improve the platelet erythrocyte overflow while the erythrocyte overflow occurs during the operation of the MCS+ Blood cell collector. Method ology：When the erythrocyte overflows or peak of platelet falls during the platelet collection process，the parameters of MCS+ blood cell collector would be modified and the collection of platelets thereafter would be noted. Results 18 of the 26 cases of collection with potential risk of erythrocyte overflow were then collected successfully after the parameters were modified，achieving a success rate of 69.2%; but erythrocyte overflow still occurred in the other 8 cases.Conclusion This study shows that parameter modification can partially reduce risk of erythrocyte overflow then increase the success rate of platelet collection，which can also lower the cost of platelet collection in terms of both labor and supplies.

Key words: Platelet, Erythrocyte overflow, MCS+, Parameter modification