Aiming at the insufficience of traditional wavelet soft and hard threshold functions and some of the threshold functions in existing literatures, and to propose an improved wavelet threshold denoising algorithm. A new threshold function is presented, which has better smoothness and changes with the changes of wavelet decomposition scale, so it has good adaptability. Besides, it improves denoising stability as a result of that there is no uncertain parameters in the function. Compared with traditional soft and hard threshold functions, that uses of the improved threshold function denoising, signals' SNR and MSE are better. Wavelet threshold denoising based on improved wavelet threshold shows an excellent effect, which has good promotional value.