Abstract: [Objective]To evaluate the toxicity of Spirulina and to provide theoretical basis for the clinical medication safety. [Methods]Kunming mice were used as experimental animals. In the acute toxicity assessing experiment, the mice were intragastrically administrated with different concentrations of Spirulina aqueous solution to determine its median lethal dose （LD50） and maximum tolerance dose （MTD）. In the subchronic toxicity evaluating experiment, mice were fed a diet containing 10.0, 5.0 and 2.5 g/kg of Spirulina for 28 consecutive days, respectively. The clinical signs, body weight, feed utilization rate, white blood cell count, blood biochemical indexes and histopathological lesions in mice were observed on 28^th day after administration. [ Results] No dead mice were observed in the acute toxicity assessing experiment; while the LD50 of Spirulina was not determined, the MTD was determined as 10 g/（kg·BW）. There were no significant differences in clinical signs, body weight, feed utilization rate, white blood cell count, blood biochemical indexes between the three Spirulina administration groups and control group （P〈0.05）; no histopathological lesions in solid organ were observed. [Conclusion] Spirulina has no acute toxicity but good safety in mice.