The utility model relates to a timing device which is composed of a main machine and an auxiliary machine. The host machine is composed of a code sending part, a key controlling part, a counting decoding part, a second pulse producer, a controller, an alarming part, a detecting part, and a digital display part, and the auxiliary machinery is similarly composed of a code receiving part, a counting code identifying part, a second pulse producer, a controller, an alarming part, an efficiency part, a detecting part, and a digital display part. The auxiliary machine adopts a large screen for display and has the same structure as the host machine basically, but the auxiliary machine is controlled by the keyboard of the host machine. The output of the host machine is displayed by three character-display tubes whose ranges are 000-999. The mode of the display is countdown timing display, three figures can be displayed at arbitrary codes, '0' is displayed when the counting is over, and the alarm signals is sent out. The utility model adopts a countdown timing mode and a large digital screen for display and has the advantage of convenience for use on large fields and the ability of enhancing the time sense of the fields.