Objective To explore clinical effect of Jiawei Sangju decoction combined with oseltamivir in the treatment of influenza B complicated with benign acute childhood myositis(BACM).Methods Sixty children with influenza B complicated with BACM hospitalized in the Department of Pediatrics,Wenzhou Hospital of Integrated Traditional Chinese and Western Medicine from January 2021 to January 2024 were selected and divided into control group and study group according to random number table method,with 30 cases in each group.The control group was treated with oseltamivir,and the study group was treated with Jiawei Sangju decoction combined with oseltamivir.The clinical efficacy,symptom improvement time and aspartate transaminase(AST),alanine transaminase(ALT),creatine kinase(CK),creatine kinase isozyme(CK-MB),lactate dehydrogenase(LDH)and myoglobin(Mb)before and after treatment were compared between two groups.Results After treatment,the total effective rate of study group was significantly higher than that of control group(χ2=5.455,P=0.020).The duration of fever and leg pain relief in study group were significantly shorter than those in control group(P<0.05).After 5 days of treatment,the levels of AST,CK,CK-MB,LDH and Mb in two groups were significantly lower than before treatment(P<0.05),and the levels of AST,CK,CK-MB,LDH and Mb in study group were significantly lower than those in control group(P<0.05).Conclusion Jiawei Sangju decoction combined with oseltamivir can improve the symptoms of influenza B with BACM,reduce the levels of muscle enzyme and Mb,and have a positive effect on the prognosis of children.