A method of converting a traditional staircase into a dual-use staircase, for reducing the stepping height and knee stress in stairs climbing and descending, comprises: providing a plurality of lifting modules and a plurality of extending modules; connecting the plurality of lifting and extending modules in pairs to the original steps respectively; and optionally connecting a plurality of dividers in between said lifting and extending modules respectively.The dual-use staircase structure reduces the step rise by half, while keeping the total run about the same. It allows healthy people to walk in a full-step domain, while allowing people with knee concerns to walk on a half-step domain. The dual-use staircase may include dividers with lateral openings to facilitate reverse turning halfway during ascending or descending of the staircase.