An embodiment of the invention discloses a face-slimming method applied to a series of images captured by an electronic device. The process begins to receive a current image from the series of captured images and detects at least one face landmark corresponding to a face region of the current image. The face landmark of the current image is compared with a reference landmark and a distortion mask is adjusted accordingly. And then, a size of the face region within the current image is then adjusted according to the distortion mask, where the distortion mask corresponds to positions of the face landmark.