A fabrication method of a semiconductor stack structure mainly includes: singulating a wafer of a first specification into a plurality of chips; rearranging the chips into a second specification of a wafer so as to stack the chips on a substrate of the second specification through a plurality of blocks; forming a redistribution layer on the chips; and performing a cutting process to obtain a plurality of semiconductor stack structures. Therefore, the present invention allows a wafer of a new specification to be processed by using conventional equipment without the need of new factory buildings or equipment. As such, chip packages can be timely supplied to meet the replacement speed of electronic products.