Methanol has currently become an excellent alternative fuel for reducing emissions and improving engine performance due to its wide range of production sources and excellent combustion characteristics. To address issues such as insufficient power at low speeds, excessive supercharging at high speeds, and poor economy of methanol engines, a one-dimensional model of a high-power six-cylinder methanol engine was established based on GT-Power. A one-dimensional simulation model was built, calibrated, and validated. On the basis of the original engine's exhaust turbine, an electrically assisted turbocharging system was established by coupling a motor. Specifically, electric supercharging is adopted at low speeds, and turbine energy is recovered for power generation at high speeds to achieve energy conservation and emission reduction of the methanol engine. The influence law of motor/generator power on the comprehensive thermal efficiency of the methanol engine was studied. The results show that the efficiency of the compressor and turbine is the key factor affecting the comprehensive efficiency. The electrically assisted turbocharging system can improve the overall efficiency of the methanol engine by 0.7% and enhance the low-speed power performance, with a power increase of 6.9%.