The microwave photonic (MWP) beamforming chip is a crucial component for achieving the miniaturization of optically controlled phased array radar systems. It addresses the unwanted ‘beam squint’ effect of traditional electronic antenna arrays in processing wideband RF signals through optical tunable delay lines (OTDLs), which has garnered significant attention and research efforts in recent years. This review provides a comprehensive overview of the latest research progress on the classification, working principle, calibration and delay measurement methods, driving and control technologies, and system function verifications of OTDL and MWP beamforming chips. Also, discussions about the challenges that need to be addressed and the future development trends for this technology are given.