Here we humanized 3G3 to have a SDR-grafted antibody, SG003, whose affinity to bind to CD38 was higher than Daratumumab, and the epitope of SG003 was different from that of Daratumumab; moreover, SG003 showed stronger ADCC function and in vivo inhibitory efficacy of tumor growth in xenograft mice model, suggesting its potential to achieve improved curative effect in patients with leukemia. The gene discussed is CD38; the disease is leukemia.