Objective To transfect siRNA into Hep2 cells for knocking down plateletderived growth factor (PDGFB) mRNA, and to detect its effect on the proliferation of Hep2 cells. Methods Four groups of PDGFB targeted siRNA were transfected into Hep2 cells with lipofectamine 2000 as vector. The expression of PDGFB mRNA and PDGFB protein was detected by realtime PCR and Western Blot respectively. MTT was used for detecting the inhibitory rates of proliferation. Results Realtime PCR showed that the expression of PDGFB mRNAs in siRNA2, siRNA3, and siRNA4 groups was inhibited with the highest inhibitory rate in siRNA2 group. The differences of the expression levels of PDGFB mRNAs in siRNA2, siRNA3, and siRNA4 groups and those of the siRNA2, the negative control and the empty liposome groups were statistically significant (P<0.05). Western Blot showed that the expression of PDGFB protein in siRNA1, siRNA2, and siRNA3 groups declined with the lowest expression in siRNA2 group. The expression of PDGFB protein in siRNA4, the negative control and the empty liposome groups were not inhibited. The MTT assay showed that siRNA1, siRNA2, and siRNA3 could inhibit cell proliferation with the most obvious inhibitory effect on siRNA2. The differences of the inhibitory rates of cell proliferation in siRNA1, siRNA2, and siRNA3 groups and those of the siRNA4, the negative control and the empty liposome groups were statistically significant (P<0.05). Conclusion siRNAs targeting PDGFB can downregulate the expression of PDGFB gene and the knockdown of PDGFB mRNA can inhibit the proliferation of Hep2 cells effectually.