Abstract: To explore the essence of the cold start difficulty of methanol engine,a transparent intake port was constructed based on the outer contour modification strategy. The effects of inlet temperature,inlet flow rate and injection pressure on intake port spray characteristics of methanol and gasoline were visually studied by using optical distortion correction technology. The results show that the increase of inlet temperature improves the spray area and reduces the spray wet wall length to a certain extent,in which gasoline presents a better effect than methanol. The inlet flow promotes the development of methanol and gasoline spray and makes the spray area of methanol larger than that of gasoline. However,the spray wet wall is serious at high inlet flow rate. Increasing the injection pressure increases spray penetration and spray area,but the spray wet wall length is also increased. It is also found that a better spray characteristic can be obtained at the inlet flow rate of 15-30 m~3/h and the intake port relative injection pressure of 0.2 MPa.