Abstract: The superior material properties with wide bandgap, large critical electric field, and high saturated electron velocity, in combination with the high density and high mobility two-dimensional electron gas induced at the AlGaN/GaN heterojunction by polarization discontinuity, and thus the related high electron mobility transistors, make GaN devices become new high performance electronic devices for next-generation power and RF applications. The demand for GaN-based power devices with excellent performance in emerging technology such as electric vehicles and AI is rapidly increasing. GaN single-chip power integration technology is the key approach to reduce the influence of parasitic inductance, improve the switching speed of IC, cut down the power consumption and realize the miniaturization for the whole system. Based on GaN single-chip power integration technology, this review paper presents a comprehensive and global overview for the research progress of the reported double-heterojunction based epitaxial structure with p-/n-channels, monolithic heterogeneous integration, All-GaN integrated circuits, and the core technology of p-channel devices.