The Low-altitude economy (LAE) is an emerging economic model, which mainly uses unmanned aerial vehicle (UAV) network to promote logistics, agricultural operations and emergency services. With the development of UAV network, UAV network system is vulnerable to threats such as GPS spoofing attacks and sensor attacks. This paper introduces the existing technologies to the security of the UAV network, and analyzes the security threats that UAV network may face. In addition, by integrating theoretical knowledge and existing methods, this paper proposes a security scheme for the UAVs, communication relays, and ground stations. The scheme emphasizes the adoption of suitable protection strategies under different threat levels, aiming to improve the UAV network security system while maintaining the efficiency of operation. This paper will promote the security of UAV network and sustainable development of LAE.