Abstract: The corn starch liquid density impairs the quality and ratio of corn starch directly, and the density mesurement still ues the proportion instrument. This paper proposes. The design and implementation methods of hardware and softeare of realtime testing and processing system for the corn starch liquid density is proposed. The system is of such advantages as simple structure, low cost, high accuracy, and high reliability. This system is suitable for applications not only in the automatical density measurement dynamically，continually and steady of corn starch liquid, but also in the concentration measurement of acids, alkalis, salts, and other corrosive liquids， So that it is with a great potential of applications in production practices.