Abstract: In response to the development trend of large-scale, complex, and intelligent space missions, this paper addressed the trajectory optimization challenges faced in space target cooperative exploration missions by reviewing the principal technological methods of spacecraft trajectory optimization. These methods include the current state of research and advancements in optimal control methods, intelligent optimization methods, and machine learning approaches. Based on this, the paper further explored trajectory optimization scenarios, mission design issues, and optimization characteristics represented by space debris removal, Earth observation satellites, small body exploration, and in-orbit servicing. Finally, the paper discussed the existing research challenges and anticipated the design requirements for trajectory optimization, aiming to provide new technological perspectives and solutions for future complex space missions.