Objective:To observe the effect of salidroside on erythropoietin (EPO) level and bone marrow pathology in rats with high altitude polycythemia (HAPC) after intervention, and to explore the mechanism of salidroside in preventing and treating HAPC.MethodsForty SPF Wistar rats were randomly divided into normal control group, model group and high, middle and low dose groups with 8 rats in each group. Except the normal control group, the other 4 groups duplicated HAPC rat models according to the methods from the literature. Salidroside was administered to the high, middle and low dose groups by gavage at doses of 200 mg/kg, 100 mg/kg and 50 mg/kg respectively, while the equal volume of 0.9% NaCl solution was administered to the model group and the normal control group by gavage respectively. All groups were intervened for 40 days.The levels of EPO in serum and kidney were determined by ELISA and Western blot respectively. Pathological smears of bone marrow were made. After HE staining, the morphology, classification and cytological counting of bone marrow cells were observed under microscope.  Results:①Compared with the model group, EPO levels in kidney and serum of rats in the high, middle and low dose groups were significantly reduced, and the difference was statistically significant (P<0.01). In particular, the down-regulation of EPO level in serum was significantly dose-dependent. ②The bone marrow erythron of rats in the low dose group proliferated actively, mainly the orthochromatic erythroblasts; Compared with the bone marrow erythron of rats in the model group, no obvious morphological change was found in the low dose group, and there was no significant difference in each index (P>0.05).③Although there was erythroid hyperplasia in the bone marrow of rats in the middle dose group, the hyperplasia of orthochromatic erythroblasts and mature erythrocytes was not significant, the morphology of mature erythrocytes was normal, and the ratio of granulocyte to nucleated erythrocyte was significantly different from that in the model group (P<0.05).④The proportion of bone marrow granulocyte series and erythron in the high dose group tended to be normal.Compared with the model group, the proliferation of orthochromatic erythroblasts was not active, the morphology of mature erythrocyte was normal, and the proportion of nucleated erythrocyte, the proportion of granulocyte and the ratio of granulocyte to nucleated erythrocyte in the test were significantly different (P<0.01).  Conclusion:Salidroside can regulate the overexpression of EPO in HAPC rats and improve the excessive compensatory proliferation of bone marrow erythron.