The coupling loss factors are important in SEA (statistical energy analysis) for predicting vibrational energy distributions and power flows between coupled structures. The traditional empirical and analytical methods for determining these parameters were either for high‐frequency range or for coupled structures with very simple geometric shapes. Analytical results are presented in this paper, which can be used to determine the energy distributions and power flow between coupled structures and so the coupling loss factors at any frequency and for any structure shape. The numerical tests for the two coupled plate system is conducted by using the analytical results, and are compared with the SEA predictions and previous experimental results in the high‐frequency range.