Abstract: An analytical design method for the LEO constellation configuration with constant trajectory was provided，where all satellites share a common subsatellite trajectory and the trajectory is fixed.The constellation configuration was coded with two parameters，the regressor and the number of satellites.Firstly，based on the idea of average orbital elements，an analytical model of repeat ground track orbit design was established under the condition that the harmonic order of the Earth’s non-spherical perturbation band is J4.Secondly，according to the relative motion law of the satellite and Earth，the analytical formula satisfying the common trajectory condition was established.Finally，the constellation configuration design model of the LEO constant trajectory constellation was constructed by combining the concept of repeat ground track orbit design and common trajectory design.The ultimate simulation results show that the configuration design method meets the design expectation，which verifies the effectiveness of this configuration design method.The constellation configuration is characterized by simple form，easy maintenance，and wide coverage.It guarantees the consistency of orientation between the space system and ground system，which greatly reduces the complexity of satellite-ground system cooperation.

Key words: LEO mega constellations, constellation configuration design, repeat ground track orbit, common satellite sub-points trajectory, constant trajectory