In this experiment, CCL₄ was used to induce liver injury in mice.Different dosages of Spirulina are given in each group respectively for 45d.ALT activity in serum, SOD activity and MDA content in the mice's brain were assayed, the functions between the dosage of Spirulina (C) and ALT, SOD, MDA values were formed with statistical methods.Relative critical values were calculated according to these functions and their biological meanings were explained.The results show that Spirulina can reduce ALT activity, improve SOD activity and reduce MDA content, and when the dosage of Spirulina overruns a certain value, the antioxidant ability of Spirulina is reduced.The spe< ifir parameters are as follows, the niininuini effectual dosage to decrease AIT is 106.4mg/kg;and that of MDA is 121.3mg/kg, the maximum dosage to increase SOD is 385.3mg/kg.It proves that Spirulina can enhance the antioxidant ability of liver in mice and alleviate liver injury caused by CCL₄