Widespread millimeter wave applications have promoted rapid development of System in Package (SiP) and Antenna in Package (AiP). Most AiP structures take the form of flip chip on antenna substrate, where interconnect losses are caused by solder bumps, and manufacturing difficulties may be encountered for chips with fine pad pitches. Fan-out wafer level package (FOWLP) with antenna patterning on Redistributed Layers (RDL) is another method for mm-wave AiP realization. In this project a hybrid integration AiP structure is developed. The Microwave Monolithic Integrated Circuit (MMIC) chip and antenna unit are integrated with chip-first FOWLP process. By using multilayer organic substrate and fine pitch RDL interconnection, proper antenna performance and lower transmission loss can be achieved. Modified coplanar waveguide is adopted to feed 2x2 aperture array formed on RDL. Package warpage is evaluated using ANSYS and Shadow Moire measurement. The antenna realizes bandwidth 25% and gain 8.5dBi using aperture-coupled stacked patch for 60GHz digital communication system. The proposed approach is a convenient solution for the hybrid integration of millimeter wave AiP systems.