The invention discloses an oil seal pressing-in device on an automobile crankshaft. The device comprises the crankshaft. An oil seal installation shaft is formed at one end of the crankshaft. A center hole is formed in the upper end face of the oil seal installation shaft. A positioning base abuts against the upper end face of the oil seal installation shaft. A positioning pin is formed on the lower end face of the positioning base. The positioning pin is inserted into the center hole in the oil seal installation shaft in a connected mode. A vertical D-shaped double-screw bolt is formed on the upper end face of the positioning base. A pressing-in sleeve is inserted to the D-shaped double-screw bolt in a sleeving mode. A pressing nut is in screwed connection with the D-shaped double-screw bolt. A limiting support abuts against the lower end face of the oil seal installation shaft. Vertical crew rods are formed at the four corners of the limiting support. The top ends of the screw rods are inserted to a top plate in a connected mode. A D-shaped hole is formed in the center of the top plate. The D-shaped double-screw bolt is inserted into the D-shaped hole of the top plate in a connected mode. A lower limiting nut is in screw connection with the D-shaped double-screw bolt and abuts against the top plate. An upper limiting nut is in screw connection with the screw rod and abuts against the top plate. By means of the oil seal pressing-in device on the automobile crankshaft, the oil seal can be conveniently and rapidly installed to the large end of the crankshaft, and the oil seal can be prevented from being damaged.