This paper explores Professor Yu Jianer’s experience in the treatment of infantile fever. It is considered that the etiology and pathogenesis of this disease can be divided into exogenous attack or internal injury, exterior syndrome or interior syndrome, deficiency syndrome or excess syndrome. The core of the treatment is to expel pathogenic factors and support healthy qi. For those with exuberant heat, the method of clearing away heat is applied; for those with pathogenic factors in Shaoyang channel, the method of reconciling is indicated; for those with lingering of pathogenic factors due to asthenia of healthy qi, the methods such as reinforcing deficiency, strengthening healthy qi and eliminating pathogenic factors are used. The commonly used prescriptions include Qingyan prescription, Xiao Chaihu decoction and Maimendong decoction, etc., and three proven cases are presented.