Abstract: A flash light for a bicycle with the function of direction and elevation indication comprises: a casing; a ball shape compass for indication of direction; an upper side of the compass exposing out of the casing; a circuit board installed within the casing; the circuit board including a pressure sensing IC and a processor; the pressure sensing IC serving for sensing the atmosphere and converting the atmosphere into elevation; the processor being connected to the pressure sensing IC for receiving the signals from the pressure sensing IC; a display for displaying values about the elevation; a touch switch in contact with a lower side of the compass; when the compass is pressed, it will press the touch switch to actuate a power of the circuit board and thus the elements on the circuit board being actuated; and an LED lamp set installed on the lamp seat.