When millimeter wave sensor is used to measure respiratory signal of distant human body, it is easy to be interfered by environmental clutter, which leads to more noise in the signal. Therefore this paper proposes a new GA-VMD-WT denoising method. The fitness function has been designed according to the characteristics of breathing signal and then, VMD parameters are optimized by GA algorithm using the fitness function.The optimized VMD parameters were used to decompose the noise signal, subsequently. In the end, the denoised signal can be obtain after the wavelet threshold for the decomposition results.The proposed method not only avoids the over-decomposition problem in VMD decomposition, but also improves the SNR by 8.5025dB, 7.6642dB and 3.3637dB, respectively, compared with other traditional denoising algorithms. Experimental results show that the denoising effect of the proposed method is good, and more useful signal information can be retained.