To observe the mechanism of Ruan Ningjiao ointmentm on tissue of rat vascular endothelial growth factor (PCNA) and the influence of PCNA (VEGF) expression in rats with hyperplasia of mammary gland.Methods:A total of 56 female unpregnant rats were randomly divided into 7 groups: normal control group, model group, excipient control group, Ruzengning group, Ruan Ningjiao ointment 4.16 g/kg, 2.08 g/kg, 1.04 g/kg dose groups. Models were produced by injecting estradiol benzoate and progesterone for 30 days. Use immunohistochemical method to determine the expression of PCNA and VEGF in rats with breast hyperplasia.Results:Ruan Ningjiao ointment 4.16 g/kg, 2.08 g/kg group can reduce the expression of PCNA and VEGF, and compared with model group, the difference had statistical significance(P<0.05, 0.01).Conclusion:Ruan Ningjiao ointment can inhibit the mammary gland vascular endothelial growth factor and the expression of cell activity, and thus to control hyperplasia of mammary gland.