Abstract: The present invention discloses a gas concentration measurement device and a method thereof, which are used to measure the concentration of carbon dioxide, and wherein a single-channel infrared gas detection module is used to detect a voltage signal of a gas sample. A digital-to-analog converter converts the voltage signal into an infrared signal value. A processing module calibrates the infrared signal value with a reference infrared signal value to generate a concentration of the gas sample. The initial reference infrared signal value is the voltage value of the normal carbon dioxide concentration in the atmosphere. The processing module calibrates the voltage drift of the gas concentration measurement device with the reference infrared signal value. Thereby is promoted measurement accuracy.