A method and a system for implementing a side function key is provided, comprising: detecting whether a side of a mobile terminal simultaneously has at least two finger touch points, if yes, displaying an icon of the function key on a side of the touchscreen of the mobile terminal, and implementing a corresponding function in response to a clicking of the icon of the function key. The method and system may comprise: detecting whether one side of a mobile terminal has finger touch points, if at least two finger touch points are simultaneously detected, then displaying a function key, thereby achieving a function of the function key on a side of the mobile terminal.