A pretreatment method for transfer printing is provided. In the present invention, a cold-transfer printing carrier is dipped and rolled by pretreatment liquid, while in the prior art, it is the textile which would be printed is dipped and rolled by pretreatment liquid. In the method, the cold-transfer printing carrier (paper, plastic thin film, and metal foil) is pretreated by pretreatment liquid through a pretreatment apparatus of a cold-transfer printing machine. The cold-transfer carrier's surface with a pigment pattern printed on should be processed with a pretreatment liquid coating procedure. The processed cold-transfer carrier's surface with a pigment pattern printed on is attached to the textile, and both of them are sent to a transfer printing apparatus to complete transfer printing process. The pretreatment method solves the problems of stretching, bowed filling, and shrink-rumple which results in flaws of pattern distortion and low product quality.