The invention discloses a Y-direction transmission mechanism of an automatic pocket facing machine. A Y-direction transmission seat is provided with a bearing hole in which a rolling bearing is arranged; the front ends of two Y-direction push shafts are provided with two horizontal and vertical mounting transverse plates; a Y-direction stepper motor is provided with a first transmission gear; a synchronizing belt wheel and a second transmission gear are arranged on a transmission shaft; a belt clip is arranged above a Y-direction synchronizing belt, and is fixed on a belt clip seat; Y-direction push crossbeams are arranged in the middle parts of the two Y-direction push shafts and the two mounting transverse plates; two X-direction linear guide rails are respectively arranged on the uppersides and the lower sides of the Y-direction push crossbeams; the horizontal direction of an mouting rack is connected with a pulley; the vertical direction of the mounting rack is connected with oneY-direction vertical mounting plate; the Y-direction rear end of a feeding support is connected with the Y-direction vertical mounting plate; the lower part of the feeding support is connected with aY-direction flat guide rail plate; and a Y-direction linear guide rail is arranged below the Y-direction flat guide rail plate. The Y-direction transmission mechanism disclosed by the invention solves the problem that patterns sewed by the automatic pocket facing machine run away, and has a reasonable structure.