For the wavelet threshold denoising method,the threshold selection of wavelet was addressed based on denoising principle,and the traditional soft and hard threshold methods were descussed.On this basis,the modified threshold function was introduced.The results of experimental simulations indicate that the modified denoising method can reduce effectively the stationary and nonstationary signals generated by the impact of shocks and the constant bias. The new threshold function is of better denoising capability than the traditional functions.