A slide rail assembly comprising a first rail, a second rail, and an engaging member, wherein the first rail is connected to the side plate of the bracket assembly; the second rail is longitudinally and movably connected to the first rail; and the engaging member is connected to the second rail and comprising a contact portion, wherein when the second rail is pulled and moved along a direction with respect to the first rail to a predetermined position, the blocking portion of the arm member blocks the contact portion of the engaging member so that the second rail is blocked at the predetermined position.