The increasing demand for high-speed, large capacity data transmission between the earth and satellites may be solved by optical communications today. Otherwise, the satellite-to-earth communication will be constrained by the transmission “bottleneck”. Relevant researches have been done with promising achievements, such as the Optical Communication Demonstration System, Optical Demonstration and High-speed Link Devices, STRV-2 Experiment, Geosynchronous Lightweight Technology Experiment (GeoLITE), the Mars Laser Communication Demonstration System (MLCD) developed by the US, and the laser communication experimental devices developed by Japan. Researches have also been conducted in China in the areas of Acquisition, Pointing and Tracking (APT), optical phased array and new types of satellite-to-earth communications. There are numerous problems which are expected to be solved in the future, including improvements of APT technology, solutions of the effect of space atmosphere, high data rate with low bit error rate, and the linking between the satellite and optical network on ground. The increasing demand for high-speed, large capacity data transmission between the earth and satellites may be solved by optical communications today. Otherwise, the satellite-to-earth communication will be constrained by the transmission “bottleneck ”. Relevant researches have been done with promising achievements, such as the Optical Communication Demonstration System, Optical Demonstration and High-speed Link Devices, STRV-2 Experiment, Geosynchronous Lightweight Technology Experiment (GeoLITE), the Mars Laser Communication Demonstration System (MLCD) developed by the US, and the laser communication experimental devices developed by Japan. Researches have also been conducted in China in the areas of Acquisition, Pointing and Tracking (APT), optical phased arrays and new types of satellite-to-earth communications. There are numerous problems which are expected to be solved in the future, including improvements of APT technology, solutions of the effect of space atmosphere, high data rate with low bit error rate, and the linking between the satellite and optical network on ground.