The invention discloses an oil seal pressing-in mechanism with a guide function, used for installing an oil seal (1) in a mounting hole (4) formed between an oil seal sleeve (2) and a gear (3); an inner hole (3a) is formed in the gear (3). The oil seal pressing-in mechanism with the guide function comprises a pressing-in head (5) and an internal guide block (7) which is movably connected with thepressing-in head (5); the internal guide block (7) is provided with a projection (7a) which is matched with the inner hole (3a); the pressing-in head (5) is provided with an extrusion part (5b) used for extruding the oil seal (1); the diameter of the internal guide block (7) is a little smaller than the inside diameter of the oil seal (1); the oil seal (1) can be arranged on the internal guide block (7) in a sleeving manner. For the oil seal pressing-in mechanism provided by the invention, through design of the internal guide block (7), the oil seal (1) can be stably installed in the mountinghole (4) without the phenomena of slanting and the like, and thus the sealing performance is improved.