Introduction to System Air-cushioned headbox presents remarkable effect on improving cross direction ration needed for the production of middle- and high-speed paper machines. Its control system focuses on the control of total head and liquid level. Frequency conversion technology has been widely spread and applied in papermaking industry. In the above headbox control system, application of frequency converter to control rotation speed of the sizing pump can successively control the liquid level of the headbox. This control on liquid level of headbox can also be realized through adjusting return flow volume of the sizing pump. The system adopts Siemens PLC from S7 series as the major control part to achieve all control functions Technical Performances Process flow: display real-time process flow with control points and setting values, measured values, sampling values and output values of relevant process parameters. A light touch on the speed button can achieve the setting of current speed. The system will automatically confirm current total pressure set value and control it according to the speed/total pressure meter. Real-time curve: display real-time total pressure, measured liquid level & setting value through curves. Renewed time can be revised online. Historical query: it is available to search for working records of a continuous month and to display it with curves. Parameter setting: it is classified as process parameter setting and control parameter setting.