High-speed swept source based on optical frequency-domain imaging is a new generation of optical coherence tomography (OCT). It is one of the hot topics in area of OCT and biomedical optical imaging due to its superiorities in speed and sensitivity over traditional time-domain technique. This paper summarizes current status and advances achieved in high-speed swept laser source. Technologies and applications of the swept laser source based optical frequency-domain imaging are introduced. Existing issues and future trends are also discussed.