In order to discard the Gaussian white noise mixed in radar signal, researched conventional wavelet threshold denoising method. By anlysing the character of soft and hard thresholding functions and some improved thresholding functions, introduces two optimized functions: improved continuous thresholding function and eclectic thresholding function. It also makes a simulation with optimized threshold. The simulation results show that the new thresholding functions above are continuous and easy to adjust, which overcome the shortcomings of the incontinuous hard thresholding function and the soft thresholding function with unvarying warp. The second method performs better, which enhances the signal-to-noise of output signal effectually. The work has an important applied value for radar signal processing.