With the complication and intelligence of space science tasks in the future, there is a high requirement for on-orbit application technology of payloads. Satellite mission planning is an important part of satellite ground application system, which determines the quality of satellite payload working. The satellite tool kit (STK) is conducive to solving the problems related to satellite orbit information, thus the development cost of mission planning system based on STK is greatly reduced. In this paper, a synthetic aperture radar (SAR) mission planning system based on STK is presented, which realizes compensation for satellite orbit offset through time compensation algorithm; coordinated planning for multiple payloads based on time logic; rapid generation for work parameters based on updating configuration files. The practical application of this system shows that it has certain application value.