As a new type of technology, the integrated system of underwater wireless optical communication and radar will play a huge role in realizing flexible and high-speed communication links between underwater vehicles, underwater monitoring points, and marine vessels. It plays an important role in wireless sensor networks, ocean exploration and detection. This paper proposes an integrated system of underwater wireless optical communication and radar, which integrates the functions of communication and radar in the same system. A time-slot synchronous clock recovery method is proposed to recover communication signals and achieve high-reliability communication; a high-precision target imaging algorithm based on the first photon is proposed to achieve high-precision radar imaging. The communication performance is verified by simulation, and the influence of radar imaging quality is verified by experiment. The results show that the system can not only achieve the function of single-photon wireless optical communication, but also achieve the high-quality target imaging of single-photon level. © 2023 SPIE.