Abstract: The performance evaluation indexes for matching torque converter with diesel engine are so many that it is difficult to determine their index weights. In order to solve this problem. The optimization method on matching torque converter with diesel engine for wheel loader based on performance evaluation mesh figure was put forward in this paper. The performance evaluation indexes matching torque converter with diesel engine for wheel loader included five items, such as the rated conditions approach degree, the activation energy degree, the economic zone tolerance, the power delivery constant, and the fuel consumption coefficients. The five matching performance indexes were defined and calculated, respectively. According to the size of the calculated value, the performance evaluation mesh figure about matching torque converter with diesel engine for wheel loader was constructed. This figure aimed at optimizing the minimum area of the performance evaluation mesh figure, constructing the objective function, optimizing hydraulic torque converter effective diameter. The original size of hydraulic torque converter effective diameter was 0.360 m, the effective diameter of the optimized hydraulic torque converter on wheel loaders was 0.350?m. After optimization, the matching performance of engine and torque converter was increased by 5.7%. Based on performance evaluation mesh figure, the optimization method improves the performance of matching torque converter with diesel engine.