Disclosed in the present invention is a motor vehicle seat floor slide rail having a gap elimination structure, comprising a lower slide rail assembly (100) and an upper slide rail assembly (200), with a gap elimination mechanism (230, 230') thereof comprising a gap elimination cam (231L, 231R) which is shaft-provided on at least one end in a longitudinal direction of the upper slide rail, and a rotation centre (232a) axis of the gap elimination cam (231L, 231R) being perpendicular to the longitudinal direction of the upper slide rail; a gap elimination face (113L, 113R) extending in a longitudinal direction of an aluminium slide rail (110) is provided on a bottom face of a locking window face (117L, 117R) on the aluminium slide rail (110), and when the upper slide rail assembly (200) and the lower slide rail assembly (100) are in a locked state, a cam face (2311L, 2311R) of the gap elimination cam (231L, 231R) is in contact with the gap elimination face (113L, 113R) under the action of a force (F), to eliminate a Y-direction gap and a Z-direction gap between the upper slide rail assembly (200) and the lower slide rail assembly (100); and in an unlocked state, a locking mechanism (240) drives an action of the gap elimination cam (231L, 231R), such that the cam face (2311L, 2311R) of the gap elimination cam (231L, 231R) loses contact with the gap elimination face (113L, 113R). The gap elimination cam (231L, 231R) of the present invention moves in linkage with the locking mechanism (240), reducing sliding friction, and having the advantage of low sliding assistance motive power.