Optical coherence tomography (OCT) is a noninvasive high-resolution three-dimensional imaging technology that has been extensively used in medicine, thin-film material fabrication, and other fields. OCT is particularly applied in ophthalmic disease diagnosis and is widely recognized as the gold standard for cross-sectional retinal imaging in ophthalmology. However, the development of applications in the traditional OCT system is limited as it comprises discrete bulky optical components. Recently, the introduction of photonic integrated circuit (PIC) technology and integration of the traditional discrete components of OCT systems into optoelectronic chips have enabled OCT systems to come into a new phase that features smaller size, lower cost, and stronger stability. This review discusses the operating principle and key performance parameters of the OCT system, including the resolution, imaging speed, imaging depth, and signal-to-noise ratio. Additionally, it outlines the design methodology of PIC-based OCT. Furthermore, this review provides a comprehensive overview of recent advancements in OCT systems based on a PIC. It assesses the strengths and weaknesses of various material platforms for OCT system applications and analyzes potential challenges encountered by current research on PIC-based OCT systems. Finally, it presents a perspective on future development directions and potential research opportunities.