For the problem of difficult cold start of methanol engine in low temperature, the effects of injection timing on low temperature combustion after cold start and unregulated emission were studied on a direct injection spark ignition methanol engine retrofitted from an 1130 single cylinder diesel engine by heating intake temperature to 283 K from 266 K based on CFD AVLFire coupling chemical kinetics reaction mechanism simulation. The simulation results show that retarding the injection timing can improve the incylinder combustion and reduce the unburned methanol emission due to the complete combustion of incylinder mixture. When the injection timing retards from 53°BTDC to 49°BTDC, the unburned methanol emission reduces remarkably. In addition, the formaldehyde emission increases when injection timing retards from 57°BTDC to 49°BTDC, but when it continues to retard to 45°BTDC, the combustion temperature exceeds 1 200 K so that the formaldehyde oxidizes rapidly and its emission becomes less obviously .