In order to solve the inefficient and time-consuming detection problem of artificial drunk driving and realize the rapid non-contact screening of drunk driving, this paper designed a set of non-contact measurement system based on the tunable laser measurement method to detect the concentration of alcohol gas in the air. The alcohol characteristic absorption peak of 3.345 μm band was used as the characteristic data and the second harmonic algorithm was used to measure the gas. The experimental results showed that the alcohol gas concentration had a good correlation with the second harmonic integral value R2=0.971. At the same time, it is verified that the detection limit of alcohol gas by the second harmonic integral area method of tunable laser can reach 50 mg/100 mL. It is proved that the method of using tunable laser to measure the second harmonic integration has a good effect on alcohol gas detection and provides theoretical support for the practical application of drunk driving detection.