A portable dual-channel digital/analogue hybrid lock-in amplifier(LIA) is developed,and its amplitude detection error is less than 10% when the signal-to-noise ratio(SNR) is larger than-12 d B.Then,a differential mid-infrared methane(CH4) detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector.The experiments are carried out to obtain the sensing performance of the device.With the absorption length of only ~4.8 cm,the limit of detection(Lo D) is about 71.43 mg/m3,and the detection range is from 0 mg/m3 to 5.00×104 mg/m3.As the concentration gets larger than 714.30 mg/m3,the relative detection error falls into the range of-5%—+5%.Two seven-hour-measurements are done on the CH4 samples with concentrations of 1.43×103 mg/m3 and 4.29×103 mg/m3,respectively,and the results show that the maximum relative error is less than 5%.Because of the cost effective incandescence wire-source,the small-size and inexpensive dual-channel LIA,and the small-size absorption pool and reflector,the developed device shows potential applications of CH4 detection in coal mine production and environmental protection. A portable dual-channel digital / analogue hybrid lock-in amplifier (LIA) is developed, and its amplitude detection error is less than 10% when the signal-to-noise ratio (SNR) is larger than -12 d B. Then, a differential mid-infrared methane (CH4) detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector. The experiments are carried out to obtain the sensing performance of the device. ~ 4.8 cm, the limit of detection (Lo D) is about 71.43 mg / m 3, and the detection range is from 0 mg / m 3 to 5.00 × 104 mg / m 3 .As the concentration gets larger than 714.30 mg / m 3, the relative detection error falls into the range of-5% - + 5% .wo seven-hour-measurements are done on the CH4 samples with concentrations of 1.43 x 103 mg / m3 and 4.29 x 103 mg / m3, respectively, and the results show that the maximum relative error is less than 5% .Because of the cost effective incandescence wire-source, the small-size and inexpensive d ual-channel LIA, and the small-size absorption pool and reflector, the developed device shows potential applications of CH4 detection in coal mine production and environmental protection.