A method and a device for generating a blurred image, and a mobile terminal are provided. The method includes the followings. According to preview image data acquired via two rear cameras of a dual-camera device, first depth-of-field information for a foreground region and second depth-of-field information for a background region in a current preview image are determined. In addition, a basic value of a blurring degree is acquired according to the first depth-of-field information and the second depth-of-field information. Furthermore, Gaussian blur process is performed on the background region according to the basic value of the blurring degree to generate the blurred image.