A video taking device comprises a video camera, an auxiliary controller and a main controller, wherein the video camera is electrically connected with the auxiliary controller and the main controller and the auxiliary controller is electrically connected with the main controller. The video camera is configured to film to generate a video stream. The auxiliary controller is configured to determine whether there is a target existing in the video stream, and to generate a switch instruction when the target exists in the video stream. The main controller is configured to switch into a first operation mode from a first standby mode and instruct the auxiliary controller to be in a second standby mode when receiving the switch instruction, and to obtain the video stream from the video camera for recognizing appearance of the target.