Abstract: Objective: To construct a siRNA expression plasmid targeting Sox9 and to investigate its effect on thegrowth and apoptosis of human chondrosarcoma cells. Methods: After designing and synthesizing the siRNA expressionplasmid, it was transfected into HTB-94 human chondrosarcoma cells and confirmed by enzyme digestion analysis andDNA sequencing. The expression of Sox9 mRNA and protein was assessed and cell growth and apoptosis were observed. Results: Compared with that of untransfected cells, the expression of Sox9 mRNA in transfected HTB-94 cells was re-duced by 35.4%, and the protein expression was reduced by 31.3%. The light absorbance values in transfected cells after24h and 96h were 0.146± 0.037 and 0.412± 0.036, but were 0.152± 0.0367 and 0.607± 0.029 in untransfected cells. Thecell growth in transfected cells was 32% lower than that in untransfected cells. The apoptosis rate was 39.2% in transfect-ed cells and 0.1% in untransfected cells. Conclusion: After transfection into HTB-94 human chondrosarcoma cells, asiRNA expression plasmid targeting Sox9 reduced mRNA and protein expression, inhibiting growth and causing apoptosisof the tumor cells.