In order to solve the problems of aluminum powder floating，sagging，color difference and adhesion between layers during the construction of “waterborne metallic basecoat+varnish”system for rail transit vehicles，the effects of low hydroxyl waterborne acrylic resin，waterborne acrylic emulsion and waterborne polyurethane dispersion on theconstruction performance of metal paint and the appearance of paint film were investigated.The results show that the combination of waterborne polyurethane dispersions with differentglass transition temperatures can effectively solve the“wet-on-wet”coating problem in the “waterborne metal flash basecoat+varnish”system，wherein the coating prepared by the combination of Bayhydrol 3 resin and Bayhydrol 4 resin has the best comprehensive performance.