Abstract: The basic research was made on the application of liquefied petroleum gas (LPG) to motorcycle engine. The experimental system adopted electronic control system of LPG injection to control fuel-feeding system. Through the study on the control characteristics of air fuel ratio and its influence factors, the authors put forward and verified the optimal control scheme with LPG injection pressure and evaporation temperature as the adjusting parameters and duty ratio as the master-control parameter. Thus they provided the reasonable basis for scientifically utilizing LPG and implementing the effective matching between electronic control injection system and engine so as to realize intelligent control.