The authors proposed a method of control and stabilization for laser emission wavelengths and power, and presented the mid-infrared wavelength tunable laser with broad emission spectrum band of 9.19~9.77 μm, half wave width of 4 cm-1, spectral resolution of 2.7×104 and max power of 800 mW with fluctuation ＜0.8% in the present paper. The tunable laser was employed as the light source in combination with ATR sensor for glucose measurement in PBS solution. In our experiments, absorbance at the five laser emission wavelengths, including 1 081, 1 076, 1 051, 1 041 and 1 037 cm-1 in the 9R and 9P band of the laser emission spectrum, all correlates well with the glucose concentration (R2＞0.99, SD＜0.0004, P＜0.000 1). Especially, the sensitivity of this laser spectroscopy system is about 4 times as high as that of traditional FTIR spectrometer.