Objective To investigate the effects of high-fat diet rich in n-3 or n-6PUFA on the expressions of Srebp2 and Hmgcr in SD rat. Methods Normal male SD rats were randomly divided into 3 groups, including normal control group (NC), high n-3PUFA formula diet group (TUF) and high n-6PUFA formula diet group (SUF). After 8 weeks, serum total cholesterol (TCH) was measured. Srebp2 and Hmgcr gene expressions were detected by quantitative real-time PCR and the proteins were observed by Western blotting. Results Serum TCH in TUF group and SUF group were both significantly lower than the NC group (P <0.001), TUF group was the lowest. Meanwhile, gene expressions of Srebp2 and Hmgcr in TUF group and SUF group were both significantly higher than the NC group (P =0.007, P =0.012). According to Western blotting, HMGCR in the TUF group is higher than NC and SUF, while it wasn’t significantly different between SUF and NC group; as to SREBP2, there wasn’t significant difference of the three. Conclusions Overfeeding of n-3 or n-6PUFA reduces rat’s serum TCH, which is not resulted from the expressions of the Srebp2 and Hmgcr.