Non-dispersive Infrared (NDIR)spectroscopic technique based on Lamber-beer law is used to detect trace gas in air.In the Lamber-beer law,approximation absorbance is linear to gas concentration.So we can make use of the low concentration of calibration gas and multilayer calibration correction to get the Lamber-beer law calibration.And quantitative analysis of the trace gas is performed by this calibration curve.This method avoids excessive curvature error of high concentration and two point calibration correction.The experimental results show that the method has good precision for quantitative analysis.