Package structures, PoP devices and methods of forming the same are disclosed. A package structure includes a first chip, a redistribution layer structure, a plurality of UBM pads, a plurality of connectors and a separator. The redistribution layer structure is electrically connected to the first chip. The UBM pads are electrically connected to the redistribution layer structure. The connectors are electrically connected to the UBM pads. The separator is over the redistribution layer structure and surrounds the connectors.