Abstract: Due to the uncertainty in deep space exploration,mission planning technology is required for deep space probes to realize autonomous control. In view of the complex function and coupling operation constraints of deep space mission planning,the extensible states are defined based on the state knowledge framework. Based on the analysis of involved constraints in mission planning,the extensible state based planning algorithm is proposed. And the designed structure of extensible states is able to prune irrelevant search space,accelerate the searching process and improve the planning efficiency. The comprehensive experiments are carried out and the computational results indicate that our algorithm can reduce nearly half of the planning steps,accelerate the process of problem solving,and improve the efficiency of mission planning