The invention relates to a valve and particularly relates to an output-force-adjustable pneumatic diaphragm regulating valve. The output-force-adjustable pneumatic diaphragm regulating valve comprises a valve body, a valve rod, a valve seat, a valve element and an actuating mechanism, wherein the valve body is provided with a runner; the valve seat is arranged on the runner and is provided with a throttling hole; the valve element is connected to the valve rod; the actuating mechanism is used for driving the valve rod to axially move to drive the valve element to open/close the throttling hole; and the actuating mechanism comprises an air chamber, a valve opening diaphragm for forming the wall of the air chamber and driving the valve rod to open the valve element, a valve closing spring for driving the valve rod to close the valve element, an extrusion block supporting against one end of the valve closing spring and a driving rod for driving the extrusion block to extrude the valve closing spring to change the deformation quantity of the valve closing spring. The invention provides the output-force-adjustable pneumatic diaphragm regulating valve capable of increasing or reducing an output force of a pneumatic diaphragm actuating mechanism online in a way that the valve or the actuating mechanism is not changed, and therefore, the problem that the output force is changed by replacing the type of the valve or a valve actuating mechanism of the existing pneumatic diaphragm regulating valve is solved.