【Objective】 To investigate the reasonable serological detection method by analyzing the characteristics of anti-K and anti-Wra from a patient who received treatment with daratumumab. 【Methods】 Unexpected antibody screening and identification were performed by saline method, polybrene, cardioagglutinin, dithiothreitol (DTT) treatment, trypsin treatment and papain treatment in the patient's plasma and acid elution solution. Heat elution test was detected after absorbing patient serum with K antigen negative red blood cells. The characteristics of antibodies were analyzed and their titer was continuously detected. Cross matching was performed after excluding interference of daratumumab. 【Results】 Anti-K and anti-Wra were detected in saline and polybrene in the patient's plasma. The patient's elution solution contained daratumumab. DTT or trypsin treatment excluded interference of daratumumab but papain treatment did not. DTT treatment destroyed K antigen and missed the detection of IgG antibodies in the Kell system. Trypsin treatment did not affect K antigen and can detect IgG antibodies of Kell system(anti-k)in the serum of the patient treated with daratumumab. Anti K was IgM and the titer was 4 by saline method and it decreased to no agglutination in room temperature after 39 days. Anti-Wra was IgG and the titer by polybrene method was 4, and it decreased to 1 after 39 days. After 76 days, neither anti-K nor anti-Wra could be detected. Transfusions of K and Wra antigen negative red blood cells were safe and effective. 【Conclusion】 DTT treatment can exclude interference of daratumumab, but attention should be paid to missed detection of anti-K. To avoid interference of daratumumab and identify unexpected antibody, multiple methods such as DTT treatment, polybrene and trypsin treatment in combination are recommended.