The measurement method based on infrared pyroelectric principle has the advantages of convenient measurement, long life, low power consumption, etc. Therefore, gas measurement, based on infrared pyroelectric has been widely used in the gas measurement monitoring system of urban pipe network, environmental monitoring and other occasions. However, in the infrared pyroeletric gas measurement, there will be multi-frequency interference signal mixed in output signal, which directly leads to low measurement accuracy. To solve this problem, infrared pyroelectric gas measurement method based on Goertzel algorithm was proposed, and the signal acquired by the AD was processed by digital filtering. Simulation analysis and comparison of filtering effect between Goertzel algorithm and moving average algorithm was finished. The simulation results show that Goertzel algorithm has filtering error of only 0.166 7%, variation size of the measurement result is only 0.058%, and its accuracy and stability are 51 and 18.4 times better than the moving average algorithm, respectively. Finally, an experiment system was built, and the measured results show that Goertzel filter algorithm can effectively improve measurement accuracy and stability of the gas concentration, and the measurement accuracy can reach ±4 ppm.