A sliding rail assembly includes a securing member, a slider, and a positioning member. The securing member is elongated in shape. A fixed positioning structure is disposed on one end of the securing member. The slider is elongated in shape and engaged with the securing member. The slider is slidable longitudinally with respect to the securing member. The positioning member is disposed on the securing member and corresponding in position to the fixed positioning structure. The positioning member is slidable longitudinally with respect to the securing member. The positioning member includes a movable positioning structure. The fixed positioning structure and the movable positioning structure on each end of the securing member are different types for selection according to demands.