In order to improve the response characteristics of the methanol injector, a one-dimensional simulation model of the methanol injector was built based on the AMEsim hydraulic simulation platform. Through the single factor analysis of the structural parameters such as the diameter of the control plunger, the preload force of the needle valve spring, the diameter of the spray hole, and the inlet and return oil throttling holes, the influences of the structural parameters on the response characteristics of the injector was researched. The parameters and their interaction were optimized by variance analysis using design of experiment method. The results show that changing the diameter of the return oil orifice has the most significant effect on the injector opening response, while changing the inlet oil orifice diameter has the most significant effect on the injector closing response. After comprehensive consideration of all parameters, the optimal parameter configuration is determined. The diameter of the control plunger is 8.8 mm. The pre-tightening force of the needle valve spring is 599.972 N. The diameter of the oil inlet orifice is 0.31 mm. The oil return orifice is 0.55 mm, and the diameter of the jet orifice is 0.86 mm. With this parameter configuration, the response characteristics of the methanol injector are significantly improved. And the opening response time and closing response time of the optimized design reduced by 28.7% and 21.1%, respectively, compared with the original state.