Low Earth Orbit(LEO) broadband constellation satellite communication is an important supplement to the ground 5G wireless communication system, and it always faces the problems of large number of ground visible satellites and high computational complexity of traditional satellite selection algorithms. In order to achieve efficient satellite grouping selection algorithm, based on the principle of Multiple Input Multiple Output(MIMO) system, the large-scale path loss model is taken as the basis, combined with the decreasing satellite selection algorithm, so as to reduce the computational complexity and approach the optimal capacity performance with faster convergence speed effectively. The algorithm is verified by numerical simulation under the typical LEO constellation system configuration, and provides a reference for the future 5G low-orbit satellite constellation communication transmission scheme design.