A fabrication method of a semiconductor package is provided, which includes the steps of: forming a packaging substrate on a first carrier; bonding a second carrier to the packaging substrate; removing the first carrier; disposing a chip on the packaging substrate; forming an encapsulant on the packaging substrate for encapsulating the chip; and removing the second carrier. The first and second carriers provide the thin-type packaging substrate with sufficient rigidity for undergoing the fabrication processes without cracking or warpage, thereby meeting the miniaturization requirement and improving the product yield.