Mobile network device and method of sharing screenshots and computer-readable medium thereof

A sender device for sharing screenshots comprises a detection module, a control module and a wireless network interface. The detection module detects in the background whether a user is executing a screenshot activity and outputs a corresponding trigger signal. The control module electrically connects with the detection module and retrieves the last taken screenshot according to the trigger signal output by the detection module. The wireless network interface electrically connects the control module for establishing a wireless network link with a receiver device and transmitting the screenshot to the receiver device. The abovementioned sender device is able to simplify the operation to share screenshots.