In some remote areas, due to complex terrain and outdated infrastructure, due to complex terrain and outdated infrastructure, traditional ground communication networks often cannot cover, resulting in blind spots. In order to better address the challenge of power detection services in remote areas, a satellite-terrestrial cell free multiple input multiple output rate splitting multiple access communication system is constructed, and the problem of maximizing user rates in the system was investigated. Firstly, the problem is modeled as a mathematical optimization problem, and then an alternating optimization algorithm is proposed to decompose the problem into active and passive beamforming sub-problems for iterative solution. Afterwards, the optimal solution of the original problem can be obtained through alternating iterative calculations. Finally, numerical simulations verified the effectiveness of the proposed algorithm and demonstrated the improvement effect of introducing RIS technology on the performance of the system model.