A sliding auxiliary device includes an assembly of a rotating wheel, a gate linked to the rotating wheel, and a toggle mechanism. The toggle mechanism includes a first arm pivoted to the rotating wheel, a second arm pivoted to the first arm, and an elastic member disposed between the first arm and the second arm. The rotating wheel substantially drives the first arm and the second arm of the toggle mechanism to relatively move to store energy in the elastic member, and the elastic member releases the stored energy to generate an acting force to assist the rotation of the rotating wheel after the first arm of the toggle mechanism crosses over a reference axial line, to obtain an improved operation smoothness better than the conventional skills.