In order to study the influence of methanol and gasoline blended fuel with different mixing ratios  on the combustion and emission performance of gasoline engine, a 1.4 L direct injection engine that was equipped with intake port injection system was retrofitted to an engine with methanol inlet injection (MPI) and gasoline direct injection (GDI). The engine model was established by using CFD technology and the incylinder mixture formation, combustion and emission performance were further studied under different methanol substitution ratios. The results show that the incylinder temperature gradually decreases with the increase of methanol substitution ratio, but decreases slowly at the ignition timing and the mass of nonevaporated fuel increases rapidly for the mixture formation. As for the incylinder combustion, the increase of methanol substitution ratio can effectively accelerate the incylinder combustion process, improve the peak cylinder pressure and peak heat release rate, shorten the ignition delay period and combustion duration, and advance the barycenter of combustion process, but the trend of accelerating combustion process slows down under a high methanol substitution ratio. In addition, NOx emission gradually increases and total CO emission reduces, but the peak CO emission first increases and then decreases, and THC emission that is mainly composed of unburned methanol gradually increases with the increase of methanol substitution ratio.