Abstract: Power distribution in the fuel rod is simulated by Monte Carlo program, and the thermodynamic behavior of the fuel rod is simulated by the fuel rod performance analysis program. Model to calculate the effective temperature of the fuel rods resonance is established, and the simulation program FRET is developed to simulate the mechanism for the fuel rod resonance effective temperature. The comparison with the calculation results from the SMART program in the SCIENCE program package showed that the FRET program can accurately simulate and calculate the resonance effective temperature of the PWR without the burnable poison fuel rods. The FRET program does not require the user to input the weighted experience data of the fuel effective temperature and can be used to calculate different types of fuel rods, which is with more extensive applications, compared with the related calculation program used in the engineering.