A slide rail assembly includes a rail and a reinforcing member. The rail includes an upper wall, a lower wall and a longitudinal wall connected between the upper wall and the lower wall. The reinforcing member is attached to the rail and includes an upper wall, a lower wall and a middle wall connected between the upper wall and the lower wall of the reinforcing member. The upper wall and the lower wall of the reinforcing member correspond to the upper wall and the lower wall of the rail respectively. The middle wall of the reinforcing member corresponds to the longitudinal wall of the rail member.