The frontier progress in collaborative control of unmanned systems in low-altitude environments is reviewed. Firstly, the importance of the low-altitude economy and relevant policy support are elaborated on, and it points out that the complexity of the low-altitude environment poses multiple challenges to the collaborative control of unmanned systems. Subsequently, the traditional and intelligent collaborative control methods are introduced in detail, and the advantages, limitations, and relevant research results of each method are analyzed. Then, the application practices of unmanned system collaborative control technology in fields such as logistics distribution, urban governance, emergency rescue, and military reconnaissance are discussed. Finally, future research directions are looked forward to, including the deepening of collaborative theories for complex dynamic environments, the expansion of collaborative control theories for heterogeneous unmanned systems, and the exploration of collaborative optimization theories empowered by quantum computing, etc., providing a reference for the further development of collaborative control of unmanned systems in low-altitude environments.