The invention belongs to the technical field of LED chip mounters, and provides a clamping mechanism for a special chip mounter of an LED display screen. The clamping mechanism comprises an air cylinder, linkage mechanisms, an X-direction and Y-direction correcting and positioning mechanism and a clamping jaw assembly, and is characterized in that the X-direction and Y-direction correcting and positioning mechanism comprises drawer guide rails, the clamping jaw assembly comprises a front moving plate, a rear moving plate, an X-direction clamping jaw and a Y-direction clamping jaw; the air cylinder is fixedly installed on an air cylinder fixing plate, a cylinder of the air cylinder is connected with the rear moving plate, a piston head of the air cylinder is connected with the front moving plate, the X-direction clamping jaw and the Y-direction clamping jaw are respectively connected with the front moving plate and the rear moving plate; the linkage mechanisms are symmetrically arranged between the air cylinder fixing plate and the front moving plate and between the air cylinder fixing plate and the rear moving plate; the drawer guide rails are respectively arranged in parallel between the X-direction clamping jaw and the air cylinder fixing plate and between the Y-direction clamping jaw and the air cylinder fixing plate, and the direction of the guide rails is consistent with the moving direction of the air cylinder. The clamping mechanism can ensure that the clamping jaws can clamp components simultaneously in the X-direction and the Y-direction when moving, keeps equidistant movements at the central position and is more accurate and rapid in correction and positioning.