In order to make better use of the advantages of RIS to save transmit power and improve system energy efficiency, the problem of how to choose the most suitable surface in multi-RIS scenarios is solved in this paper. This paper proposes a "minimum path product" selection scheme based on the characteristics of the RIS-assisted communication cascaded signal path loss model, and uses transmit power and energy efficiency as evaluation indicators. D2D communication user scenarios are simulated. The simulation results show that the "minimum path product" option is slightly better than the "minimum path sum" option in terms of saving transmit power and improving energy efficiency. Therefore, in the general RIS application scenario, according to the characteristics of the far-field path loss channel, using the "minimum path product" is the optimal choice.