A side-plate stabilizing structure of a drawer comprises side-plate elements, a base plate, a front plate, a rear plate and a sliding rail component. The sliding rail component is used for opening and closing the drawer. A locking and separating device connected with the front plate and a rear connecting device connected with the rear plate are arranged on the side-plate elements, a stabilizing rod is arranged on the upper sides of the locking and separating device and the rear connecting device, and the stabilizing rod, the side-plate elements, the locking and separating device as well as the rear connecting device jointly enclose to form a cavity, and a plate is arranged in the cavity. By the improvement of the above structure, the problem about unstable structure due to the fact that side plates are designed too high is effectively solved, the drawer is stable and firm in structure and swings weakly in use; the stabilizing rod, the side-plate elements, the locking and separating device as well as the rear connecting device jointly enclose to form the cavity, the plate is arranged in the cavity, the plates can be made of materials like wood, stone, glass, plastics or metal, outside attractiveness of the drawer can be further improved, and practicability is high.