Objective To investigate the effect of transplantation of bone marrow mesenchymal stem cells (BMSCs) and anti-aging gene (Klotho gene) on cardiac remodeling in rats under chronic hypoxic condition. Methods Rat model of cardiac remodeling was established in a hypoxic chamber of 10% oxygen for 28 d. The rats were divided into model group, BMSCs group and Klotho group, and another normal control group for isolation, culture and identification of BMSCs. Recombinant lentival vector of Klotho gene was constructed. After the establishment of the model, the BMSCs and lentival vector of Klotho were transplanted into the chronic hypoxia rats by tail vein. In 4 weeks after the infusion, the contents of procollagenⅠcarboxy-terminal propeptide (PⅠCP) and PⅢCP in the serum and myocardial tissues were detected by ELISA. The morphology of cardiomyocytes was observed by HE staining, the content of myocardial collagen was detected by MASSON staining, and the apoptotic rate of myocardial cells was detected by Tunel. SPSS statistics 17.0 was used to analyze the data. The measurement data were expressed as mean±standard deviation ([AKx-D]±s), and Student’s t test was employed for the comparison between groups. Results After 4 weeks’ transplantation of BMSCs and Klotho gene, the serum and myocardial contents of PⅠCP and PⅢCP, collagen volume fraction (CVF) and apoptotic rate of cardiomyocytes were significantly lower in the BMSCs group and Klotho group than the model group (P<0.01). Compared with the Klotho group, the BMSCs group had significantly lower apoptotic rate of myocardial cells (P<0.01). Conclusion BMSCs and Klotho gene transplantation can both effectively reverse cardiac remodeling, and BMSCs is superior to Klotho gene in resisting myocardial cell apoptosis.