This paper introduced the components, principle and the hardware and software design of the multiplexing measuring and control instrument to the liquid level that is based on MSP430 SCM. This system is made of pressure sensor, signal processing circuit,electromagnetic valve, output driving circuit, Chinese character LCD, keyboard, optic alarm circuit and MSP430MCU, and realized Liquid level automatic monitor, out range alarm and online function. Keywords: Liquid level measurement;Master-slave communication; MSP430SCM;V/F convert