Space-based laser altimetry, which measures the planetary surface topography based on time-of-flight ranging, is an important technology for earth and deep space exploration. The development history and current status were sorted out systematically and development in three directions was proposed, including multi-beam observation, underwater terrain observation of offshore and islands and laser active multispectral detection. It was suggested that some key technologies should be developed, including infrared single photon detection, ultra-narrowband optical filtering, multiphoton resolution detection, single-photon data on-board preprocessing and high conversion efficiency laser and nonlinear optical frequency conversion, to promote the further development of Chinese space laser altimetry technology.