Multitarget rendezvous can effectively reduce the cost of a single mission and increase the benefit, so it is the first choice for asteroid exploration, inorbit service and other missions in the future. The trajectory optimization problem of such missions involves many variables and huge solution space, so it is difficult to obtain the optimal solution directly. The solution of this problem is usually divided into two steps: first, the rendezvous sequence is optimized, and then, for a given rendezvous sequence, the trajectory of each targettotarget transfer is optimized. Fast and accurate estimation of the transfer cost such as velocity increment or transfer time is needed to optimize the rendezvous sequence. Thus, the trajectory optimization problem of multitarget rendezvous can be divided into three subproblems: transfer cost estimation, rendezvous sequence optimization, and transfer trajectory optimization. In this paper, the methods of solving these three subproblems are summarized.