The invention relates to a quantitative calculation method of boiler superheated steam temperature by feed water temperature change, characterized by, including the input of benchmark parameters and operation parameters, Calculation of standard coal consumption rate for power generation, Calculation of boiler efficiency, Calculation of heat consumption rate of steam turbine unit, the calculation of superheated steam temperature, the calculation of reheat steam temperature, Compared with the prior art and analysis method, the present invention is comprehensive in consideration, clever in algorithm conception, scientific, reasonable and accurate in calculation method, and can realize the accurate quantitative calculation of the superheated steam temperature of the boiler due to the change ofthe feed water temperature, thereby accurately guiding the corresponding operation adjustment of the boiler feed water temperature change, so as to be beneficial to the safe and economic operation ofthe boiler.