The aim of the present study was to investigate the effect of Lycium barbarum polysaccharides (LBP) on the treatment of ITP mice and to explore its mechanism. Forty idiopathic thrombocytopenic purpura (ITP) mice were divided randomly into a model control group and LBP groups I, II, III and IV. ITP mice in LBP groups I, II, III, and IV were administered LBP at four different doses (50, 100, 200 and 400 mg•kg −1 •d −1 , respectively) for 7 days by gavage. Blood samples were collected from the tail veins of the mice after treatment. Platelet counts were determined, and the total antioxidant status (TAS), total oxidant status (TOS) were measured with ELISA kits. The platelet count was (30.28 ± 13.42) × 10 9 /L in the model control group, and the number of platelets in all LBP groups was higher than that in the model control group. The platelet count increased, and it reached (67.09 ± 10.81) × 10 9 /L in LBP group I; the platelet counts in the other three groups increased significantly compared to LBP group I, and they did not differ significantly. TAS concentrations in the LBP groups were significantly increased compared to the model control group, whereas TOS concentrations were significantly decreased. Taken together, these results indicate that LBP is effective at increasing the number of platelet (PLT), and LBP may treat ITP mice via suppressing oxidative stress.