At a certain frequency or in a band, one or several acoustic radiation modes which make a major contribution to the acoustic potential energy are defined as DARMs (dominant acoustic radiation modes) of coupling enclosure. The determination of DARMs is of virtual importance, and it directly affects the effect of active structural acoustic control. However, the current determination methods either one-sidedly emphasize the effect of radiation efficiency while ignoring the impact of modal amplitude, or require the knowledge of structural modes which was difficult to be extracted in engineering applications. To overcome these problems, comprehensively by the means of computation and testing, and fully considering both radiation efficiency and modal amplitude, a method based on “primary election-reservation-posteriori correction” was proposed to determine DARMs in coupling enclosure, and an experimental research was performed to verify the effectiveness and feasibility of the proposed method. Results show that the proposed method can accurately identify DARMs and does not require the knowledge of structural modes throughout the process, so it can be used to guide the selection of control objective or reconstruct the acoustic potential energy of coupling enclosure.