The invention provides a method, a chip and a device for implementing the functions of compound keys of the key module of an embedded system. The method comprises the following steps: the embedded system executes keystroke interruption and records the keystroke after detecting the keystroke is pressed; the embedded system starts a timer and then rescans if other keystrokes are pressed in accordance with scheduled time intervals, if so, records the new keystrokes; the embedded system scans if all the keystrokes are released, and then disables the timer if all the keystrokes are released; then the embedded system produces the key assignments of the compound keys according to the keystroke records and submits the program prior to the keystroke interruption. The timer is additionally arrangedin the system on the basis of the existing array keystroke module. The system starts the timer and then rescans and records other keystrokes in accordance with the scheduled time intervals after detecting a keystroke interruption. Therefore, under the condition of one system interrupted, the invention can realize the functions of the compound keys by obtaining the responding of a plurality of keystrokes. Besides, the proposal of the invention has no restriction to the keystroke sequence and quantity, and supports the composite of any keystroke and a plurality of keystrokes.