Time of flight(TOF) three-dimensional imaging technology has the advantages of active parallel detection in the frame, good real-time acquisition of scene information, small influence of ambient light, high accuracy of detection data, strong anti-sport interference and low average power consumption. In three-dimensional intelligent sensing, industrial inspection, SLAM and other fields have a wide range of applications, especially in autonomous navigation, driving control and intelligent systems as a real-time three-dimensional imaging information of the sensor has been rapidly developed. The principle and characteristics of two kinds of TOF imaging were studied. Two types of TOF imaging principle and characteristics, system composition were discussed. TOF imaging system was compared with other mainstream three-dimensional imaging technology. Its main source of error and type was classified and analyzed, its error model was studied. As a new generation of three-dimensional imaging technology, TOF is still in the development stage, which can effectively enhance the imaging perception and measurement level of the intelligent system and promote the technological progress in related fields.