A buckle locking structure device for the rear compartment cover of pickup trucks, comprising a cross rod aluminum extrusion, a slider, a T-rod, a buckle block, a handle, a T-insertion block and a frame body aluminum extrusion, its features are: when the slide hole channel of slider is installed on the cross rod aluminum extrusion, the slider can move back and forth on the cross rod aluminum extrusion quickly and easily, when the T-rod is connected to buckle block, handle and barrel bolt and fixed to the slider, a buckle locking structure device is formed, the buckle locking structure device is equivalent to that the slider can be moved quickly and easily on the cross rod aluminum extrusion to the region to be buckled, with the groove face on the two side walls inside the U-slideway of handle and the structure of shoulder edge part slot of the groove face, when the handle is to fasten down, the shoulder edge part slot of groove face formed on both side walls inside the U-slideway of handle can fasten along the semi-circular arc flanges on both sides of the lug at the bottom of buckle block.