The structural intensity technique can directly measure and distinguish power transmissions between different structural wavetypes across a joint, and its applications are numerous in practical engineering. In this paper, a new method is proposed for the measurement of coupling loss factors (CLFs) using the structural intensity technique. An outline of the method’s theory is also given. Theoretically the proposed method gives an approximate estimation of CLFs. The approximate error depends on the ratios of the effective modal overlap factor of the receiving subsystem to the modal overlap factors of the subsystems coupled through the joint of interest. If the effective modal overlap factor of the receiving subsystem is large compared with the modal overlap factors of the coupled subsystems, the approximate error is small and negligible. A series of measurements were carried out to verify the outlined theory. The results measured on the joints with two subsystems showed that this proposed method can be used to accurately measure CLFs when the modal overlap factor of the receiving subsystem is larger than that of the source subsystem. The approximate error decreases with increasing frequency and the modal overlap factor ratio of the receiving subsystem to the source subsystem.