The study of Unmanned Aerial Vehicle (UAV) swarms has grown to be a central research domain in recent years due to their significant advantages such as mission efficiency, environmental adaptability and structural robustness. In recent years, the study of UAV swarms has gained increasing attention, because it can improve the navigation and positioning capabilities of UAVs in Global Navigation Satellite System (GNSS) denial environment. Based on the introduction of the advantages and development status of UAV swarms, the collaborative navigation and positioning technology of UAV swarms in GNSS denial environment are studied. The collaborative navigation organizational structure of UAV swarms, as well as the collaborative navigation information fusion architecture and algorithm of UAV swarms are analyzed. Finally, the key technical issues of collaborative navigation are sorted out and prospected.