Abstract: After the installation of three-way catalytic converter, universal gasoline engines often experience significant power loss. In order to solve this problem, we employed numerical engine simulation technique to explore a high-efficiency performance optimization method based on one-dimensional simulated engine by using GT-power software. The optimization method was applied to simulate the performance of a 125 mL universal gasoline engine and optimize its design. A performance optimization approach was formulated and prototype trial-production and experiments were carried out. The optimized engine performed better after the installation of catalytic converter than it did before the installation. The proposed performance optimization method was validated accurate, efficient and worth applying in the engineering field.