The invention discloses a cold extrusion forming process for an oil pump shaft for an automobile. The cold extrusion forming process comprises the following steps of: 1, blanking; 2, performing phosphorus saponification for the first time; 3, shaping and punching to form a guide positioning pit; 4, performing spheroidizing annealing; 5, performing shot blasting; 6, performing the phosphorus saponification for the second time; 7, performing backward extrusion to obtain a pre-cooling extrusion piece in which a bottom edge is reserved and which has a hollow straight wall; 8, annealing; 9, punching the bottom edge of the pre-cooling extrusion piece; 10, rectifying deviation and lathing an excircle, a flat head, a fillet and a tear strip; 11, performing the phosphorus saponification for the third time; and 12, performing forward extrusion, and pressing to form a cold extrusion piece for the oil pump shaft. By the cold extrusion forming process for the oil pump shaft for the automobile, the oil pump shaft for the automobile is subjected to extrusion forming once, so that the slight cutting or no cutting of complex pipe fittings is implemented.