The invention relates to a workpiece tray transfer device which comprises a temporary storage table and at least one stock bin in joint with the temporary storage table through a rail. The temporary storage table is provided with a lifting mechanism. The stock bins are provided with clamping mechanisms. Each clamping mechanism comprises two oppositely-arranged clamping hands which are arranged on the two opposite sides of the corresponding stock bin respectively. Each clamping hand comprises a clamping board with a step. The clamping boards are sequentially connected with vertical air cylinders and horizontal air cylinders, or the clamping boards are sequentially connected with the horizontal air cylinders and the vertical air cylinders. The temporary storage table is arranged so that workpieces can be transferred and sorted through trays in batches; the temporary storage table is effectively jointed with the stock bins, so that it is guaranteed that the trays can automatically pass the temporary storage table one by one and the workpieces are detected nearby. The temporary storage table is lifted through the lifting mechanism, it is guaranteed that the horizontal height of the trays at the bottoms of the stock bins and the horizontal height of the temporary storage table can be kept identical, and therefore it can be guaranteed that a push-pull mechanism can well transfer the trays smoothly along the rail.