The actual working conditions of oil extraction are complex and changeable. When using the conductometric method to measure the water content online, the environmental factors, temperature, salinity and the electrode structure of the sensor itself will bring about measurement deviations. In this paper, three-electrode and four-electrode with different electrode ring inner diameter and excitation electrode spacing are designed for comparative experiments, and conductivity and temperature information were obtained by calibration experiments. Considering the nonlinearity caused by temperature and signal conditioning circuit, the comprehensive compensation function is established and optimized by the least square method to obtain the temperature and nonlinear comprehensive compensation parameters. The performance of the sensor is optimized by optimizing the electrode structure and compensating parameters. The water content testing system was established for simulation testing and verification. Experiments show that the measurement error of the sensor optimized and compensated for the electrode structure parameters is within 2%, and the stability is good, which can meet the measurement of crude oil water content.