1. A mobile device capable of identifying images offline and online synchronously, comprising: an image capturing unit for retrieving frames of a recognition target; a processor for performing offline image recognition on the frames, and determining whether the mobile device is operatively connected to Internet; and a display monitor for displaying a recognition result; wherein, upon determining the mobile device is not operatively connected to the Internet, the processor performs offline image recognition on the frames and displays an offline recognition result of the offline image recognition as the recognition result on the display monitor; and wherein, upon determining the mobile device is operatively connected to the Internet, the processor performs offline image recognition on the frames and simultaneously sends the frames to a recognition server via the Internet so the recognition server performs synchronous online image recognition on the frames, receives an online recognition result of the online image recognition, determines whether the online recognition result has a recognition value higher than a recognition value of the offline recognition result, in case of the recognition value of the online recognition result is higher, displays the online recognition result as the recognition result, else displays the offline recognition result as the recognition result.