A slide rail assembly includes a first rail; a second rail movable relative to the first rail; a third rail mounted between the first rail and the second rail; a first sliding auxiliary device movably arranged between the first rail and the third rail, the first sliding auxiliary device comprising at least one first rolling member and a first meshing feature, the least one first rolling member configured to facilitate the third rail to move relative to the first rail; a second sliding auxiliary device movably arranged between the third rail and the second rail, the second sliding auxiliary device comprising at least one second rolling member and a second meshing feature, the least one second rolling member configured to facilitate the second rail to move relative to the third rail; and a synchronizing member meshed between the first meshing feature and the second meshing feature.