Objective To investigate the effect of quality control circle (QCC) application in reducing incidence of oral mucositis in children with acute lymphoblastic leukemia (ALL) during chemotherapy. Methods We founded QCC team and established Reducing incidence of oral mucositis in children with as the subject, conducted survey, analyzed the reasons for the occurrence of oral mucositis, set goals, developed countermeasures, and conducted effect evaluation. Results The incidence of oral mucositis in children with ALL was 14.86% in the experimental group compared 39.19% of the control group (χ2=22.20, P<0.01), both were lower than the goals and achieved our aims. The severity in the experimental group was significantly lower than that the control group in oral mucositis incidence (P<0.05). Conclusions QCC application can not only reduces incidence of oral mucositis in children with ALL, but also improves the responsibilities and quality management capabilities of QCC members, and promotes the continuous improvement of the quality of nursing in Department of Hematology. Key words: Children; Quality control circle; Acute lymphoblastic leukemia; Oral mucositis; Chemotherapy