A denoising and baseline correction method based on wavelet transform and their parameters choosing method were developed to remove noise and correct baseline in the spectrum effectively. Baseline wander was removed by setting approximation coefficients to zero

and noise was removed by the method of threshold detail coefficients of higher-frequency period in wavelet filed

and with simulated signals of pure spectrum and familiar baseline and noise

the parameters such as wavelet basis

decomposed level

threshold selection rule and so on were chosen by the evaluation coefficient η which considered approaches of integral signal and every characteristic peak simultaneously. The simulated experiment shows that it is more suitable that the simulated signal is decomposed at level 5 on the wavelet basis of sym5、db5、db9 and so on

and then the approximation coefficients are set to zero and threshold detail coefficients by hard threshold with single layer Heursure threshold selection rule. Further experiment shows that this method provides a novel and to correct effective way to remove noise and to correct baseline in the real spectrum.