The deep-sea AUV/ARV is an important technical equipment for hadal scientific research, engineering and military applications. Focusing on the AUV/ARV with maximum operating depth of 6000 meters or more,the research status and application fields of the deep-sea AUV/ARV are introduced,the key technologies such as overall design and integration,deep-sea structure and materials,high-efficiency energy power,high-speed underwater communication,combined positioning and navigation,and autonomous sensing and control that need to be broken through are analyzed,and the future development trend is prospected.