In this paper, recent research progress of optical wireless communications in unmanned aerial vehicles (UAVs) was reviewed. By means of wireless optical technology, technical challenges and key enabling technologies were also surveyed for implementing robust and wideband communication links between UAV and satellite, UAV and UAV, and UAV and terrestrial terminals. The mechanisms and schemes of modeling, parameter optimization, and experimental testing under different UAV optical wireless link configurations were described in detail. Additionally, the key development trends of high-speed and high-reliability UAV-based wireless optical communication technology in modular implementation, high altitude platforms applications, and others were discussed.