Embodiments of the disclosure provide a package structure and method of forming the same. The package structure includes a first die, a first encapsulant, a first RDL structure, a die stack structure and a second encapsulant. The first encapsulant laterally encapsulates the first die. The first RDL structure is electrically connected to the first die, and disposed on a first side of the first die and the first encapsulant. The die stack structure is electrically connected to the first die and disposed on a second side of the first die opposite to the first side. The second encapsulant is located over the first encapsulant and laterally encapsulating the die stack structure. A sidewall of the first encapsulant is aligned with a sidewall of the second encapsulant.