In demodulating process of optical fiber sensing,the existence of the noise is inevitable,seriously affecting system′s precision to demodulate central wavelength.The wavelet de-n oising method with its good ability of time-frequency localization,multi-resolution analysis and handlin g nonlinear problem in the field of optical fiber sensing de-noising has been widely used,and it is crucial to sel ect the optimization decomposition scale,since the decomposition scale will affect t he quality of denoising directly.Based on the analysis of conventional and proposed methods of decomposition scale selection,a multi-indicator fusing method is quoted to fuse signal to noise ratio,root mea n square error,smoothness and bias of signal into a comprehensive evaluating indicator,and process the fusion indicator with exp onential fitting algorithm and present an inflection point judgment formula to determine the optimal decompo sition scale.And then, combined with better threshold and improved threshold function,with experimenta l signal,the best decomposition scale is chosen in this presented method.The experimental results show that the reflectivity rate of central wavelength,with optimal decomposition scale selected in this method,is consist ent with the real values.Thus,the proposed method shows better performance in de -noising.