Abstract: The control rod position measurement plays a vital role on the operation and safety of a reactor. To this end, a sensor system based on the two-electrode capacitance sensor was used to measure the control rod position in NHR-200. Additionally, electrode coverage, stray capacitance and shielding method were analyzed to optimize the two-electrode capacitance sensor. The capacitances obtained by simulations were compared with experiment results to verify the measurement accuracy. The results show that the simulation results agree well with the experimental results. It is demonstrated that such a system shows very promising applications for measurements of the control rod position of nuclear reactor.