The invention discloses a servo welding slide table mechanism. The servo welding slide table mechanism comprises a servo motor, a servo motor gearbox, a gearbox output gear, a slide table transplanting car, a slide table rack, a slide table slide rail, a slide table fixed base, a slide fixture, a slide fixture Y-directional guide rail, a slide fixture Z-directional roller and a slide fixture positioning bolt; the servo motor is driven to the gearbox output gear through the servo motor gearbox; the gearbox output gear is engaged with the slide table rack, so that the slide table transplanting car moves between a mounting position and a welding position along the slide table slide rail; and the slide fixture is firstly switched in place through the slide fixture Y-directional guide rail andthe slide fixture Z-directional roller, is fixed on the slide table transplanting car through the slide fixture positioning bolt, and moves to the mounting position / welding position for welding. The servo welding slide table mechanism improves the position precision of the slide table transplanting car, solves the vehicle type flexibility problem, realizes the safety protection of mounting staff through separation of the mounting position and the welding position, and is simple in electric control and pneumatic switching to meet the production safety requirements.