The ring roads in mountainous city business districts are prone to congestion due to numerous intersections and fluctuating traffic flows. To address this, a cooperative signal control method for managing ring roads entrances and exits is proposed. Road and traffic characteristics were extracted using high-altitude video, checkpoint data, and Internet-based datasets. The control objectives include maximizing vehicle throughput, minimizing entrance queue lengths, and reducing downstream congestion at exit intersections.The optimization model is constrained by signal control parameters, queue lengths, and overall ring roads density. The standard NSGA-Ⅱ algorithm was improved in operator design and population size configuration. A MATLAB-VISSIM simulation platform was developed for joint simulation. A case study of the Guanyinqiao business district ring roads in Chongqing was conducted. Results show that, compared to the original scheme, the optimized strategy increases ring roads capacity by 8.9% during peak hours, reduces entrance lane queue length by 31.7%, and decreases exit lane queue length by 15.0%. These findings validate the effectiveness of the proposed multi-objective optimization and cooperative signal control method. By enhancing coordination among multiple intersections, this approach provides valuable guidance for alleviating regional traffic congestion during peak hours.