Abstract: Capacitance rod position measurement sensor is the key measurement equipment of control rod hydraulic drive system (CRHDS) of 200 MW Nuclear Heating Reactor (NHR200). Its accuracy and reliability are directly related to the safety of the reactor. In this paper, the theoretical model of capacitance rod position measurement sensor was established based on the finite element method. The sensitivity distribution characteristics of the detection field of two electrode capacitance rod position measurement sensor were analyzed. The results show that there is a specific area in the detection field, and the eccentricity error is smaller when the measuring rod moves to this area. Based on this feature, the design of multi electrode capacitance rod position measurement sensor and the capacitance detection method of rotating electrode were proposed. For the sensor, the finite element method was used to optimize the sensor structure and analyze the eccentricity error caused by the eccentricity of the measuring rod. The static characteristic experiment of the sensor was carried out and the model calculation results were verified. The results show that the multi electrode capacitance rod position measurement sensor and the capacitance detection method of rotating electrode can effectively use the sensitivity distribution characteristics of the detection field, and the eccentricity error of the optimized sensor can successfully reach the requirements of rod position measurement without losing step. The research results provide a new method for the design and optimization of capacitance rod position measurement sensor.