Abstract: A denoising method based on Non-local means for sequence of slice images in cone-beam CT is proposed, according to the properties of the noise and sequence of slice images of cone-beam CT system, moreover, the definition of filtering degree is proposed as well. The relation of filtering strength to standard deviation of the background zone before filtering and the structure zone of method noise images is established. Moreover, the relationship between filtering strength and the standard deviation of the background zone before filtering is established under the same filtering degree to compute the filtering strength of each slice image, which contributes to the consistency of filtering degree of all slice images. The efficiency and feasibility of this method is verified by the experiment.