Abstract: Optical gas absorption is a widespread phenomenon. Tunable diode laser absorption spectroscopy method and experiments are used to verify the fundamental gas absorption theory according to the Beer-Lambert law of optical part in physical course. The basic absorption wavelength with the different oxygen concentrations is obtained. The results show that the higher the concentration,the greater the light attenuation. Moreover,the mathematical knowledge is expanded according to the fitting curve. This experiment is helpful in widening the students＇ horizons and learning new technologies. Through this experiment, the theoretical understanding of gas absorption theory is deepened and the practical ability of students is exercised, which provides effective help for the college physics teaching process.

Key words: tunable diode laser absorption spetroscopy （TDLAS）, Beer-Lambert law, gas absorption, laser in-tensity, physics teaching