A method for sending a keycode of a non-keyboard apparatus is provided and includes the following steps. The non-keyboard apparatus determines the connection status between itself and a computer by the time required for device enumeration. Then, according to a value generated from device enumeration, the non-keyboard apparatus identifies the kind of operating system running on the computer. The non-keyboard apparatus sends to the computer a keycode corresponding to the Num Lock key and/or a keycode corresponding to the Caps Lock key such that a sending time and a feedback time are obtained. A parameter related to the efficiency of the computer is then calculated based.