The present invention relate to a seat track for a vehicle which can be adjusted forward and backward, in more detail, a seat track locking system for a vehicle which includes a plurality of locks for fixation or movement of the track that are spaced from each other by a half of a pitch thereby finely adjusting the seat track while maintaining the existing fixing-strength of the seat track. The seat track locking system for a vehicle of the present invention having the configuration described above has an effect of ensuring strength against shock and load when the seat track is fixed, and allowing fine adjustment when the seat is adjusted forward and backward.