The object of this paper concerns with the research of 8-electrode oil-water two-phase flow electrical capacitance tomography system. The distribution models of sensor’s field are established by the finite element method for the influence of the parameters of sensor’s structure on the performance of sensor. The analyses of simulation and experiment and the sensor’s optimization design are done, and the measure function of sensor’s optimization design is proposed based on sensor parameters that are listed as follows: length of electrodes, stretch angle of electrodes, thickness of pipeline, permittivity, thickness of stuff filled between screen and electrodes, radial electrodes and so on. In conclusion, the final parameters and materials adopted are proved better than those adopted before. Consequently the sensitivity and uniformity of the sensitive field is improved and the design of the measurement circuit is easier, and the data precision of sensitive field is enough for image reconstruction.