Task allocation model based on Multi-Agent theory was established according to mission planning problem of agile satellite after analysis of agile satellites characteristics and satellite multi-user demand. Agile satellite dynamic task re-scheduling model was proposed for the failure of satellite resources in the agile satellite mission planning initial program scheduling. For obtaining the optimal solution we presented agile satellite dynamic task allocation algorithm based on the agreement ending contract net, and designed bidding mechanism, contract net protocols and strategy of biding and assessing biding. Finally, agile satellite mission planning scheduling problem was taken as an example, and satisfactory results were obtained through experiments, which showed that the model was reasonable and the algorithm was efficient.