Ormia ochracea with an extremely short baseline is able to locate its specific parasitoid host (cricket) precisely. On the fact mentioned above, this paper establishes a biomimetic coupled processing system based on the Ormia ochracea to improve the performance of miniature direction finding (DF) devices. According to the mechanical model of coupled auditory structure of the Ormia ochracea, the time domain response and frequency domain response of the auditory structure were deduced and their phase difference responses were computed. Then, a signal processing model for biomimetic coupled processing system was established, and its performance was analyzed. The results show that proposed system can be used to handle arbitrary frequency signals and enhance the phase difference between signals by setting proper coupled parameters, particularly, the phase difference can be amplified about 18 times under ideal conditions. For certain coupled parameters, there exists the most sensitive frequency and the most sensitive incident angle in the system, namely, the most sensitive frequency makes the phase difference between responses arrive to 180°. Moreover, the gradient of phase difference between responses reaches its peak at the most sensitive incident angle. The biomimetic coupled processing system may adopt two kinds of mechanisms to measure directions: one is direct DF with the measurable phase differences, and the other is indirect DF by baseline rotating using the most sensitive frequency and the most sensitive incident angle concepts. This paper provides a theoretical foundation for much wider applications of the biomimetic coupled processing systems.