With the rapid development of space communication technology, there is an urgent demand for information security. Free-space optical communication based on semiconductor laser, known for its terminal miniaturization, low power consumption, wide-spectrum and no electromagnetic spectrum constraints, has been widely used in high-speed space communication. As chaotic free-space optical communication technology can encrypt optical signal in physical layer, it becomes a research hotpot of space optical communication. Combined with the current development process of free-space optical communication, chaotic laser communication and chaotic free-space optical communication, this paper introduces the key technologies of chaotic free-space optical communication, and focuses on the research progress of laser beam ’s pointing, acquisition and tracking technologies, turbulence mitigation technologies of chaotic free-space optical communication and chaotic free-space optical synchronization technology. Besides, the future research directions and several key technologies that can be used for reference of chaotic free-space optical communication are also prospected, aiming to provide reference for the further development of chaotic free-space optical communication technology.