Hardware and software design of high-precision real-time analyzer of water in oil that focuses on AT89C52 SCM is introduced. ICL7135A / D conversion is applied to realize high-precision data acquisition in the analog signal acquisition channels, method of true and false load is adopted to inhibit the interference signal in data acquisition department and data transmission channel, and the stability of data is improved through the operation of software. Digital tube is applied to display the measured value, an alarm signal would be sent out if the value exceeds the set value, and at the same time the control signal of the start of oil-water separation equipment would be given. The analyzer is constituted by SCM, shortwave emitter, data processing section, result display and some other components, the system structure is simple and reliable, and the measuring accuracy is high.