Abstract: Underwater wireless optical communication (UWOC) can provide a high-speed and flexible communication link for underwater platforms. This paper introduces the basic structure of a UWOC link and points out the optimization schemes for a UWOC system. Absorption, scattering, and turbulence will affect the performance of a UWOC system. A comprehensive study of channel characteristics can guide the design of transmitters, receivers, and related signal processing technologies. The performance of UWOC can also be optimized by multiplexing technologies, single-photon detection technologies, and alignment systems. A comprehensive test platform could provide a necessary test environment for further sea trials and the practical applications of UWOC. The paper is expected to serve as a guideline for researchers related to UWOC.