In order to overcome the slow speed of detecting trace formaldehyde in the sample gas,material consumption by chem-ical reaction,and the limitations of the sampling area in the detection of trace formaldehyde,a multi-wavelength characteristicsmethod for getting the exact concentration of formaldehyde quickly was designed.According to the spectrum characteristics offormaldehyde and the main interfering gases the system chose multiple wavelengths with the minimum degree of coherence(thenumber of characteristi...