In order to realize real-time detection of CH_4under coal-mine envir onment,by using a wavelength-modulated distributed feedback (DFB) laser whose wavelength is cent ered at 1.654μm,a stand-alone near-infrared (NIR) CH_4detection device is experimentall y proposed based on tunable diode laser absorption spectroscopy (TDLAS) technique.An intelligent temperature controller,a scan and modulation module and a cost-effective portable lock-in amplifier are developed to drive the DFB laser and extract the second harmonic signal from the differential signal between the two channels,and their performance is thoroughly measured and characterized.The device is integrated with all optical modules and electrical modules,and measurements are carried out to study its detection performance on CH₄.Exper imental results show that the relative detection error is less than 7% within the detection rang e from 0to 100%, and the minimum detection limit (MDL) is about 1.1×10－5.Long-term monit oring lasting for 24h on two standard gas samples (1×10－3 and 2×10－1) suggest good stability ,whose maximum detection errors are smaller than 7.0% and 2.5%,respectively.With similar detection princi ple and the same hardware system in this paper,this device can also be used for other gases′ d etection by utilizing a different DFB laser with the corresponding absorption wavelength.