A slide rail assembly includes a first rail, a second rail, a releasing member, a blocking member and an operating member. A first positioning structure, an assisting structure and a second positioning structure are arranged on the first rail. The assisting structure is located between the first positioning structure and the second positioning structure. The second rail is displaceable relative to the first rail and can be positioned at different positions by a blocking of at least one of the releasing member and the blocking member and one of the first positioning structure, the assisting structure and the second positioning structure. The operating member is configured to operate the releasing member and the blocking member for terminating the blocking of the at least one of the releasing member and the blocking member and the one of the first positioning structure, the assisting structure and the second positioning structure.