Multi-target space exploration is one of the options for economic, rational and sustainable space exploration ,and it can achieve huge benefits at a low cost. Due to the huge and complicated optimization space and difficulties of optimization, multi-target space trajectory optimization is a topic that attracts lots of research. Intel-ligent methods are suitable for solving these problems. In this paper, multi-target space trajectory optimization is discussed by introducing trajectory optimization competitions in which intelligent methods are playing more and more important roles. Then this paper reviews transfer trajectory intelligent optimization methods and sequence intelligent optimization, and the conclusion is drawn at last.