Aim To explore the effect of erythropoietin （EPO） on proliferation and phenotypic transformation of neonatal rat cardiac fibroblast （CF） induced by high glucose in vitro. Methods CF cells were cultured from neonatal rat primary cells. In the process of promoting the phenotypic transformation of CF cells,high glucose medium was selected for induction,and EPO was added for intervention. The same batch of CF cells were randomly divided into three groups: control group （5.5 mmol/L glucose）,high glucose group （25 mmol/L glucose）,and high glucose＋EPO group （25 mmol/L glucose with 20 kU/L EPO）. CF cells were identified by using immunohistochemistry Levels of type Ⅰ and Ⅲ collagens were detected by enzyme-linked immunosorbent assay （ELISA） Expression of fibrosis marker α-smooth muscle actin （α-SMA） was detected by Western blot. Results Immunohistochemistry staining showed that fibronectin,vimentin were positive,and α-actin was negative So,the cultured cells were CF cells. Compared with the control group,the expressions of type Ⅰ and Ⅲ collagens were significantly increased in high glucose group （P<0.01）. The expressions of type Ⅰ and Ⅲ collagens in high glucose＋EPO group were significantly lower than those in high glucose group （P<0.01）. The expression of α-SMA in high glucose group was significantly higher than that in control group （P<0.05）. The expression of α-SMA in high glucose＋EPO group was significantly lower than that in high glucose group （P<0.05）. Conclusions High glucose can effectively induce the phenotypic transformation of CF cells. EPO can reverse myocardial fibrosis induced by high glucose environment.