Stephania delavayi Diels. has been used as an immune activator or an anti-inflammatory drug in China. We examined the immune modulation effect and 7-days repeated-dose toxicity to validate its biological safety and efficiency. Mice were repeatedly administrated with 50 mg/kg S. delavayi Diels. daily by I.P for 7 days. S. delavayi Diels. induced B cell activation but had no effect on other immune cells such as T cell, natural killer (NK) cell, and macrophage ($M{varphi}$). S. delavayi Diels.-treated group exhibited no statistical significance from the control group in physical conditions; body weight, complete blood count (CBC), serum biochemical indexes etc. There was no difference between the control group and S. delavayi Diels.-treated group in gross findings such as histopathological alteration. In conclusion, S. delavayi Diels. is safe above the dose of immune modulation.