Using photodiode array (PDA) detector and spectrometer, a method on the basis of algorithm of nondispersive ultraviolet (NDUV) is described to measure and analyze nitric oxide (NO) gas. With the introduction of light source impact factor and absorption spectrum impact factor, fitting equation and correlation coefficient between absorbance and concentration was acquired through comparative analysis on the total intensity of nitric oxide absorption and non-absorption spectrum, which are collected in different integration times and within different wavelength width. The results show that second order fitting correlation coefficient related to absorbance and concentration is above 0.999 9 and the error of concentrations between the concentration calculated by fitting equation and the standard concentration is less than 3% through using suitable fitting order, fitting wavelength width and analysis method.