调节阀阀门前后压差一定，普通阀门的开度在较大范围内变化时，其流量变化不大，而到某一开度时，流量急剧变化，即调节性能不佳。调节阀可以按照信号的方向和大小，改变阀芯行程来改变阀门的阻力数，从而达到调节流量目的的阀门。调节阀分手动调节阀和自动调节阀，而手动或自动调节阀又分许多种类，其调节性能也是不同的。自动调节阀有自力式流量调节阀和自力式压差调节阀等。
The pressure difference between the front and back of the control valve is constant. When the opening of the common valve varies in a large range, the flow rate does not change much, but when a certain opening, the flow rate changes sharply, that is, the regulation performance is not good. The regulating valve can change the resistance number of the valve by changing the core stroke according to the direction and size of the signal, so as to achieve the purpose of regulating the flow rate of the valve. Regulating valves are divided into manual control valves and automatic control valves, while manual or automatic control valves are divided into many types, and their regulating performance is also different. Automatic control valves include self-operated flow control valves and self-operated differential pressure control valves.