An image processing method applied in an image processing device, which includes an image capturing unit, an image processing unit, an image recognition unit and an exposure adjusting unit, is provided. The image processing method includes the following steps: obtaining a first image by the image capturing unit, generating an average brightness of a dark part of the first image by the image processing unit; recognizing the first image by the image recognition unit; generating a first average brightness of a human face by the image processing unit and generating a first exposure value according to the average brightness of the dark part of the first image, the first average brightness of the human face and a weight array, when the human face is recognized from the first image; and adjusting an exposure of the first image according to the first exposure value by the exposure adjusting unit.