A motor vehicle seat floor slide rail includes a lower slide rail assembly (100), an upper slide rail assembly (200) and a gap elimination mechanism (230, 230′), with a shaft-provided gap elimination cam (231L, 231R), on an upper slide rail longitudinal end, having a rotation center (232a) axis perpendicular to an upper rail longitudinal direction. A locking window face (117L, 117R) has an aluminum slide rail (110) longitudinal gap elimination face (113L, 113R). A rail locked state has a cam face (2311L, 2311R) in contact with the gap elimination face to eliminate a Y and Z direction gap. In a rail unlocked state, a locking mechanism (240) drives the gap elimination cam, such that the cam face loses contact with the gap elimination face. The gap elimination cam moves in linkage with the locking mechanism, reducing sliding friction, and having the advantage of low sliding assistance motive power.