A three-dimensional numerical simulation model was developed to investigate the impact of key parameters including injection pressure, orifice diameter, injection direction, and incoming flow velocity on the droplet size distribution of methanol spray. The results reveal that increased injection pressure leads to a shift of the droplet size distribution towards smaller droplet sizes, accompanied by reduction in Sauter mean diameter（SMD）as well as characteristic diameters DV10, DV50 and DV90（DVX refers to the droplet size of the droplets which accounts for X% of the spray dropet cluster）. As the orifice diameter decreases, SMD and characteristic diameters of methanol spray droplets decrease, and the span of droplet size（SDS）and wall film quality also decrease. When the injecting angle is 45° against reverse incoming flow, more small-sized droplets are generated. Increasing the incoming flow velocity causes the spray droplet size distribution to shift towards smaller sizes, resulting in decreased SMD and characteristic diameters.