Abstract: Objective:To analyze the positive rate,specificity and influencing factors of PLT antibody detection in patients with ineffective platelet transfusion after repeated transfusion. Method:The serum samples of 80 inpatients who were ineffective after repeated blood transfusion were selected from November 2015 to November 2017 in our hospital.The platelet antibodies were detected by solid phase coagulation,and the specificity and positive rate of HLA,HPA and platelet alloantibodies were measured,and the relationship between these and sex,age,blood transfusion composition and transfusion times were analyzed. Result:The detection rate of platelet alloantibody was 64.00%（52/80）in patients with ineffective platelet transfusion,in which the positive rates of homologous HLA and HPA antibodies were 43.75%（35/80）and 21.25%（17/80）respectively,and 58.82%（10/17）HPA antibody positive patients were detected at the same time,and the positive rate of platelet autoantibody was 12.50%（10/80）.The positive rate of platelet antibody in male patients was lower than that of female patients,but the difference was not significant（P＞0.05）.Among the different types of blood transfusion,suspended red cell 70.00%（14/20）was higher than that of little white blood red blood cells 25.00%（5/20）,and 95.00%（19/20）of concentrated platelets was higher than that of single extracted platelets 70.00%（14/20）（P＜0.05）.There was a positive correlation between the number of platelet antibodies and of transfusion times（P＜0.01）.Conclusion:The homologous HLA and HPA antibodie are most common in patients with ineffective platelet transfusion after repeated blood transfusion,and the number of platelet antibodies is positively correlated with blood transfusion times,and there is an inseparable relationship between different components of blood transfusion and produced platelet antibody.