The term"guide"appears 27 times in Zhang Shi Yi Tong.ZHANG Lu's use of guide medicine belongs to the expanded application of meridian-inducing medicine.Or just as a boat,carrying and guiding other medicines to exert their effects;or use one's efficacy to lead other medicines to eliminate evil qi together;or use the clothing of a pimple as a guide for fetal toxins,carrying toxins into the body can produce a vaccine.Choosing drugs with the same properties as evil qi,the same taste as the medicine caused by drug errors,and medications with unique and effective treatment patterns as guide drugs can expand the traditional principles of selecting meridian-inducing drugs.Can provide doctors with another formulation and thinking mode,and have guiding significance for improving clinical efficacy.