A semiconductor package structure is provided. The semiconductor package structure includes a semiconductor die surrounded by a first molding compound layer. A redistribution layer (RDL) structure is formed on a non-active surface of the semiconductor die and the first molding compound layer. A second molding compound layer is formed on the RDL structure. An insulating capping layer covers the second molding compound layer. An antenna is electrically coupled to the semiconductor die and includes a first antenna element formed in the RDL structure and a second antenna element formed between the second molding compound layer and the insulating capping layer.