We designed a tunable Distributed FeedBack (DFB) laser array with a large tuning range based on Reconstruction-Equivalent-Chirp (REC) technique near the wavelength of 1650nm for the first time. We experimentally demonstrated that the laser with wavelength ranging from 1650.4nm to 1657.6nm can be continuously adjusted by selecting the corresponding channel and changing the bias current to detect methane, water vapor, carbon dioxide and carbon monoxide. Furthermore, the idea of this DFB laser for gas detection without Thermo Electric Cooler (TEC) is put forward at last.