Abstract: Based on 3D Monte Carlo particle transport code JMCT, the RPN calibration coefficients of different operation cycles of a reactor were calculated. By adopting the direct Monte Carlo method, the response matrix method and the adjoint Monte Carlo method, sets of RPN calibration coefficients were obtained, which were further used to calculate the power level and the axial power difference of the reactor. The calculated values were compared with the experimental values. The results show that all the three methods can meet the accuracy needs in engineering, among which the adjoint Monte Carlo method has least computation cost. The feasibility of calculating RPN calibration coefficient by using Monte Carlo method was validated.