According to the characteristic of Differential Optical Absorption Spectroscopy(DOAS) system,the Adaptive Neural Fuzzy Inference System(ANFIS) was proposed to evaluate the slowly varying components by using the nonlinear approaching theory of ANFIS in this paper.The network parameter can be flexibly regulated according to the measuring spectra.The testing results show that the ANFIS is more flexible than polynomial fitting and the fitting accuracy can be easily solved.The reliability and accuracy of DOAS evaluation have been improved for the application of the ANFIS.