The invention provides a state No.4 commercial automobile instrument external control status indicator lamp automatic detection circuit comprising a current sampling circuit, a signal shaping circuit, a controller array, a liquid crystal display and voice alarm circuit, and an indicator lamp switch array. The signal shaping circuit consists of a filter circuit and an amplifier circuit, and is used for filtering out noise and amplifying a sampling voltage acquired in the current sampling circuit. The indicator lamp switch array is used for simulating the operation of a switch of an automobile body on an instrument external control lamp. The controller array is used for acquiring the current in a status indicator lamp branch, the input end of the controller array is connected with the signal shaping circuit, and the output end of the controller array is connected with the liquid crystal display and voice alarm circuit and the indicator lamp switch array. The controller array controls the indicator lamp switch array through an IO port thereof so as to control on-off of an instrument external control lamp to be detected, and acquires the current of an external control lamp branch to be detected through an AD port thereof to judge whether the voltage is within a predicted range and judge whether the instrument external control indicator lamp functions normally.