A processing method for in-mold coating integrative system is used in cooperation with an injection molding machine. The injection molding machine comprises a rotatable work platform and a combination of at least one male mold and at least two female molds. The rotatable work platform is divided averagely into several work areas, and the processing proceeds sequentially in each work area by the rotation of the rotatable work platform. The processing method comprises following steps: injection molding a solid workpiece firstly, and leaving the solid work-piece on the male mold; rotating the rotatable work platform; performing surface coloring; rotating the rotatable work platform; injecting UV top-coat, the top-coat female mold is made of light-directing material and has a die cavity and a UV paint cavity on the surface of the solid workpiece, and a UV top-coat layer is injected into the UV paint cavity through a paint channel; irradiating the UV top-coat layer by a UV top-coat hardening lamp; and demolding to achieve a finished product. The method is of benefit to mass production, and can reduce labor cost and processing cost.