A method for reducing spatial noise of images includes the following steps. A target pixel is obtained and an operating block is built accordingly. Pixel values of the target pixel and multiple neighboring pixels in the operating block are operated to obtain a variance corresponding to the operating block. Whether the target pixel is characteristic is judged according to the variance. If the target pixel is not characteristic, the multiple pixels in the operating block are filtered to obtain a modulated pixel value. The pixel value of the target pixel is updated to the modulated pixel value.