Disclosed is a using method of an intelligent trimming assembly line. The intelligent trimming assembly line comprises an assembly line groove, a belt sander, a sucker manipulator and a controller. The belt sander is mounted in the assembly line groove. The sucker manipulator is mounted beside the assembly line groove. The belt sander comprises a motor, a sand belt, a driving wheel and a driven wheel. During using, the controller controls the motor of the belt sander to drive the driving wheel, the sand belt and the driven wheel to rotate. The sucker manipulator sucks and places a plate blankinto an inlet of the assembly line groove. The plate blank rolls under the gravity of the plate blank and enters a trimming and grinding channel between the sand belt and an elastic bottom plate. Thecontroller controls the belt sander to conduct trimming and grinding on burr of the plate blank rolling in the trimming and grinding channel. The plate blank after trimming and grinding passes throughan outlet of the assembly line groove under driving of the sand belt and flows into a finished product box. Unmanned machining of the trimming process of the plate blank is achieved, and the production efficiency of plate blank trimming is improved.