An optimized design approach for the capacity adjustment strategy is suggested in order to address the issue that the shifting strategy of the conventional hydro-mechanical transmission system is not suitable for the return-flow hydro-mechanical transmission with the energy contain gear. When the loader working in the V-operating mode, the ideal shift point of the adjustable device may be found using the NSGA-III optimization method in conjunction with the V-operating mode data. According to the simulation findings, the average traction of the wheel loader fitted with the PTHTS has risen by 8.32%, the transmission efficiency has grown by 9.56%, and the fuel consumption has decreased when compared to the conventional hydraulic transmission system. 1.54 percent.