The structural design of the ball valve significantly impacts the maximum pressure-holding capability of pressure-retaining coring tools. In this study, the pressure-bearing structure of the ball valve was optimized, and a theoretical model for its pressure resistance was established. Through numerical simulation, the maximum von Mises stress \({\upsigma }_{{\max}}\) and effective seal width S were established as evaluation indicators for the valve’s pressure retention performance. Based on a sensitivity analysis of the ball valve’s structural dimensions, three key design parameters were identified: the valve body inner diameter \({D}_{5}\) , the sealing surface adjustment amount \({L}_{2}\) , and the pressure surface adjustment amount \({L}_{6}\) . Using response surface methodology (RSM) and central composite design (CCD), a regression model was developed to correlate \({D}_{5}\) , \({L}_{2}\) , and \({L}_{6}\) with \({\upsigma }_{{\max}}\) and S. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) was then applied for multi-objective optimization, yielding optimal parameters: \({D}_{5}\) = 60 mm, \({L}_{2}\) = 37 mm, and \({L}_{6}\) = 35 mm, the corresponding values of \({\upsigma }_{{\max}}\) and S are 806.67 MPa and 11.02 mm, respectively. The optimized results were compared with numerical simulations, showing errors of 3.53% for \({\upsigma }_{{\max}}\) and 6.9% for S, thereby validating the accuracy of the predictive model. Compared to the initial design, the optimized configuration reduced \({\upsigma }_{{\max}}\) by 8.1% and increased S by 118.2%, significantly enhancing the pressure-bearing strength and sealing performance of the ball valve. This research proposes a novel approach to enhance the pressure-holding capacity of ball valves, providing certain theoretical guidance for improving the performance of pressure-retaining coring equipment.
