For a large number of earth observation satellites as well as ground station resources, how to effectively arrange the integrated imaging and data transmission activities plays a crucial role in improving the satellite management efficiency with the increasing quantity of observation missions. Based on comprehensive consideration of practical constraints, a mathematical model is established to describe the imaging satellite united mission planning problem in detail. A simple as well as comprehensible individual representation method is designed by adopting the idea of uniform resource encoding, and the conception of conflicting mission sets is proposed by utilizing the potential conflict relationship of the effective execution period for each mission to reduce the time complexity of solving this problem, thereby generating the corresponding algorithm framework. Finally, test instances demonstrate the effectiveness of the algorithm framework, which also shows its ability to obtain high-quality solutions within a limited time period for the large scale optimization instances.