The invention discloses a processing device for a QFN packaging device. The processing device comprises a supporting plate, a first frame, a second frame, a third frame, a marking device and a grinding mechanism, wherein the first frame, the second frame and the third frame are sequentially connected and arranged on the same side of the supporting plate; the marking device is arranged above the second frame; the grinding mechanism is arranged above the third frame; the grinding mechanism comprises a top plate and a grinding head movably arranged below the top plate; one side of the top plate is fixedly connected with the supporting plate, and a baffle plate is arranged on the other side of the top plate; an air nozzle is formed in the baffle plate; a dust collection bin is arranged below the third frame; a negative pressure fan is arranged in the dust collection bin; and a dust collection plate is arranged below the third frame. According to the processing device, double-sided markingof a semiconductor device arranged in a moving block is automatically realized without manual intervention and turnover, so that the influence on the marking precision caused by errors caused by manual turnover can be avoided, and the operation efficiency can be improved.