According to the needs of full range and high precision measurements of methane concentration in coal mine safety production monitoring system, a full-scale integrated laser methane sensor was designed based on a Tunable Diode Laser Absorption Spectroscopy (TDLAS). A 1 653.72 nm Distributed Feedback Laser(DFB) semiconductor laser was employed as the system light source. Laser driving, temperature controlling, signal modulation and demodulation, and concentration calculation were realized by a single board circuit. To meet a high measurement precision and a large dynamic measurement range simultaneously, the wavelength modulation technique was used to detect the methane at a low concentration. When the gas concentration is higher than the threshold set in the system, the direct absorption detection technique was switched to automatically. Experimental results show that, the measurement error is less than ±0.06% in the range of 0～5% and less than ±6% of the actual value in the range of 5～100%, and the response time is less than 15 s, which meets the requirements of the mine measurement in practice.