OBJECTIVE：To study the mechanism of enhancement effects of Astragalus complanatus polysaccharides（ACP） on the proliferation of meniscal fibrochondrocytes cells in rabbits. METHODS ：The meniscal fibrochondrocytes cells were isolated from 1-month-old New Zealand white rabbits. The meniscal fibrochondrocytes cells were divided into normal control group （PBS）， positive control group （glucosamine sulfate ，10 mg/mL）and ACP high-dose，medium-dose and low-dose groups （40，20，10 mg/mL）. The morphology of meniscal fibrochondrocytes cells were observed under microscope. Cell proliferation rate was detected by MTT assay. Cell cycle was observed with flow cytometry. ELISA assay was used to detect relative expression of medium collagen type Ⅱ（Col Ⅱ）and alkaline phosphatase protein （ALP）in meniscal fibrochondrocytes cells. RT-qPCR and Western blotting assay were adopted to detect mRNA and protein expression of transforming growth factor β 1 （TGF-β 1） and bone morphogenetic protein 2（BMP-2）. RESULTS ：After cultured for 72 h，meniscal fibrochondrocytes cells were fused into a single layer，and most of them were slender type in appearance. Compared with normal control group ，the proliferation rate of meniscal fibrochondrocytes cells and the percentage of cells at G 1/G0 phase were decreased significantly in positive control group and ACP high-dose，medium-dose and low-dose groups （P＜0.05）；the percentage of cells at S phase ，protein expression of Col Ⅱ and ALP，mRNA and protein expression of TGF-β1 and BMP- 2 were increased significantly （P＜0.05）. Compared with positive control group，inhibitory rate of meniscal fibrochondrocytes cells proliferation and the percentage of cells at G 1/G0 phase were decreased significantly in ACP high-dose group （P＜0.05），while the percentage of cells at S phase ，protein expression of Col Ⅱ and ALP ， mRNA and protein expression of TGF-β1 and BMP- 2 were increased significantly （P＜0.05）. The inhibitory proliferation rate of meniscal fibrochondrocytes cells and the percentage of cells at G 1/G0 phase were increased significantly in ACP low-dose group （P＜ 0.05），while the percentage of cells at S phase ，protein expression of Col Ⅱ and ALP ，mRNA and protein expression of TGF-β1 and BMP- 2 were decreased significantly （P＜0.05）. There was no statistical significance in above indexes of ACP medium-dose group. CONCLUSIONS ：ACP can promote the proliferation of meniscal fibrochondrocytes cells ，reduce the percentage of cells at G1/G0 phase，promote cell transformation to S phase ；the mechanism of which may be related to up-regulating TGF-β1，BMP-2 mRNA and protein expression ，promoting Col Ⅱ and ALP protein expression enhancement.