In the harsh measurement environment, the high-frequency interference has a great impact on the harmonic signal and reduces the measurement accuracy of gas parameters when using absorption spectroscopy method. To improve the target detection performance, frequency multiplexing based on high-frequency reference signals is proposed. The method can extract interference signals and correct the transmitted intensity of reference signal by using a high-frequency reference signal, thereby accurately extracting the harmonic sighanl of detected signal, improving the accuracy of gas parameter measurement and expanding the application range of absorption spectroscopy method. The numerical simulation and the establishment of experimental measurement system to measure the molar fraction of methane verify that the method has the advantages of excellent high-frequency interference suppression and high measurement accuracy of gas parameters.