A denoising scheme based on wavelet shrinkage technique is proposed to remove the noise in the heart sound signal. Firstly, the characteristics of heart sound signal frequency were analyzed and Haar, Daubechies, Symlets and Coiflets orthogonal wavelets were studied for contrast in accordance with the principle of frequency band similarity matching. Based on the statistical results, Coif5 wavelet was chosen for the decomposition and reconstruction of heart sound signal. Besides, a smooth and continuous adaptive elastic threshold function was designed for wavelet shrinkage, which can overcome the problem of discontinuous hard threshold function. The noise reduction effects were compared under four threshold rules. The simulation results show that, when the SNR is less than 50 dB, the optimization scheme with Heursure threshold rule can retain sufficient heart sound detail information, while effectively removing noise.