Due to the advantages of rich information, strong anti-interference ability and high resolution, three-dimensional (3D) imaging lidar has been widely used in defense and civil fields, such as geomorphology surveys, autopilot, smart transportation and visual tracking. With the development of avalanche photodiode detector (APD) and the multiplicities of 3D lidar (e.g., MEMS, optical phased array, flash, etc.), the performances of lidar has been greatly improved compared with that of initial 3D systems. According to the new requirements on 3D lidar for the military and civilian fields, novel methods and mechanisms were proposed to improve comprehensive performances of 3D imaging. First of all, the three key technologies of APD-based 3D imaging lidar were analyzed, including the transmitting unit, the receiving unit, and the algorithm unit (data processing unit). Then, 3D imaging lidar was classified and discussed according to the different applications for loading. Among them, 3D imaging lidar based on unmanned vehicle was selected as the typical example for illustrating the application status and the difficulties faced with military and civilian applications. Based on the diversified development of 3D imaging methods, two novel 3D imaging methods (heterogeneous resolution and ghost imaging) suitable for APD devices were discussed. Finally, based on the analysis of the research status of 3D imaging lidar, it is concluded that 3D imaging lidar is developing towards the large field of view, high resolution, high precision, real-time, modularity and intelligence, which paves the way for developing high performances of 3D imaging lidar.