To ensure the successful implementation of the old community renewal project (OCRP), it is essential for the participants to allocate the project risks reasonably. Firstly, this study comprehensively identifies the 20 key risk factors of the OCRP. Secondly, an index system is established from three dimensions to evaluate the risk allocation ability of participants, including a total of nine evaluation indexes. Furthermore, a risk-sharing model based on TOPSIS method and bargaining game model is proposed to determine the optimal risk bearer and risk-taking ratio between the government and the private sector in OCRP. Finally, an OCRP in Chongqing is taken as a case study to verify the applicability of the developed model. The results indicate that in OCRP under PPP mode, the government need to independently bear 7 risks related to politics, law, policy, while the private sector needs to independently bear 8 risks mainly from project financing, design, construction, operation, and maintenance stages. In addition, the risk-taking ratios of 5 risks that require both parties to share are divided. The research findings provide references for ensuring the smooth implementation of urban renewal and sustainable development.