Range extender (RE), combined by an engine and a generator, charges the battery on the electric vehicle. Power management strategy of a range extended electric vehicle (REEV) will determine the required charging power according to battery state of charge (SOC) and driver demands. The charging power demand will be further converted into required operation torque and rotational speed demands from engine. Torque-based engine management system (EMS) is, therefore, required to receive the torque command from power management strategy for controlling the engine at required torque. This research develops a torque-based EMS for a RE engine which is a 125cc four-stroke semi-direct injection engine and fueled by liquefied petroleum gas (LPG). The RE engine is operated to provide stable power output for driving generator, so we only select two operating points for this engine. The first operating point is for higher power output and better fuel economy. The other operating point is selected for noise and vibration harshness (NVH) concern with lower engine rotational speed. Simulation and experimental results show that electronic throttle control (ETC) and spark control can satisfy the torque commands and ensure the stability. This setting provides great contribution to fuel economy and emission reduction, also comfort concerns for passengers.