The invention discloses a control method used for controlling an electronic device. The electronic device comprises an imaging device. The control method includes the steps of processing, detecting, computing, judging and prompting. In the processing step, a preview image output by the imaging device is processed so as to recognize a face region and acquire the area of the face region; in the detecting step, the object distance of a face is detected; in the computing step, the distortion degree of the face region is computed according to the position, area and object distance of the face; in the judging step, whether the distortion degree is larger than a preset threshold value or not is judged; in the prompting step, a user is prompted when the distortion degree is larger than the preset threshold value. The invention further discloses a control device and the electronic device. By means of the control method, the control device and the electronic device, the distortion degree of the face is judged according to related parameters in portrait shooting, and the user is prompted when the distortion degree is larger than the preset threshold value.