A new frequency discrimination technique with high-precision called dual-frequency quad-edge technique which bases on a single solid Fabry-Perot (F-P) etalon and a tunable semiconductor laser is proposed. The function expressions of the reflection spectrum and the transmission spectrum are deduced. The frequency discrimination principle of dual-frequency quad-edge technique is analyzed. According to the frequency discrimination principle, the architecture of the frequency discrimination system and the corresponding analysis and processing methods for detection signals are given. Then, the measurement error caused by noise also is analyzed and the specific error formula is derived. The detection performance of this frequency discrimination technique is analyzed by comparing with that of the conventional double-edge frequency discrimination technique base on F-P etalon. The results show that the frequency discrimination accuracy of this frequency discrimination technique can improve 2.82 to 3.03 times through the simultaneous detection of the transmitted and reflected signals from the F-P etalon, while the optical path of this new technique is simple and the system cost is low due to the use of a single solid F-P etalon.