Abstract: With the extension of the operation period, the characteristics of narrow range temperature probe will be drifting and aging in CPR1000 units. At the same time, the change of thermal hydraulic characteristics factors will also lead to the unreasonable setting of the parameters of average temperature summary and temperature deviation summary. Therefore, it requires to modify the characteristics of narrow range temperature probe and the parameters of summary according to the cross comparison data. Aiming at the possible deviation, the modification method is put forward: the fitting modification method for three point curve of narrow range temperature probe and the fitting modification of two point curve of the average temperature summary and temperature deviation summary. And the optimization and improvement scheme is put forward, including excluding natural temperature deviation factor, weight coefficient in different operation conditions and horizontal / vertical trend comparison. These methods had been applied in the field, and were proved to be feasible and effective.