Abstract: Objective:To study the characteristics of MNS antibody and explore how to effectively reduce its interference with blood group identification and cross-matching. Method:Accidental antibody screening and identification were perfor med on 427 blood cases(from January 2015 to December 2017) of inconsistent positive and negative stereotypes and cross-incompatible ones,in order to test the nature of MNS antibody.After preparing anti-type RBC,blood samples were re-identified on positive specimens.Cross-incompatible specimens were given RBCs without corresponding antigens and cross again. Result:Of the 427 specimens,105 were positive for MNS antibodies,93 for anti-M antibodies,4 for anti-N antibodies,6 for anti-S antibodies,2 for anti-Mur antibodies,66 for IgM antibodies in female patients,9 for IgG antibodies and 6 for IgM+IgG antibodies.There were 37 cases had blood transfusion and pregnancy history,accounting for 45.68%,and 22 cases had pregnancy history alone,accounting for 27.16%.After the blood group was re-identified and cross-matched,the results showed that positive and negative stereotypes were consistent and cross-compatible.There was a lack of corresponding antigen RBC 96 unit in 46 patients.There were significant differences in Hb,RBC and Hct before and after blood transfusion(t=60.575,45.299,80.426,P=0.000).Conclusion:The MNS accidental antibody is mainly anti-M,antibody properties are mainly IgM.To deal with inconsistent positive and negative or cross-incompatible blood specimens,multiple methods should be used to detect blood types and cross matching to ensure the safety of clinical transfusion.