Energy finite element analysis (EFEA) is an effective dynamic analysis method in mid to high frequencies. When EFEA is adopted to analyze the coupled plate structures,the study on vibration energy transfer is necessary,and the energy transmission coefficients (ETCs) are required to build the energy coupling matrix. On the basis of the structures’ impendence characteristic in mid to high frequencies,the wave method is performed to acquire the ETCs of coupled plates with arbitrary coupling angle by replacing finite coupled plates by semi-infinite coupled plates with same parameters. Considering of the wave type conversions in coupled plates,the characteristics of the energy transmission are investigated in case of flexural,longitudinal and shear waves impinging,respectively. Based on the reverberation field assumption,the ETCs of certain incident angle are processed to make them compatible with the main assumption of EFEA. The influences of coupling angle,excitation frequency,and plate’s thickness on diffuse energy transmission coefficients (DETCs) and energy transmission ratio with the wave type conversion are studied. The research can be used to obtain the ETCs of coupled plates with arbitrary coupling angles when the wave type conversion is considered,and it is the prerequisite for the application of EFEA as well.