A method for measuring an actual temperature of a flame by using all information of a radiation spectrum comprises the following steps: measuring a first digital distribution spectrum of emissive power, changing with a wavelength λ, of a to-be-measured object at an arbitrary known temperature by using a digital spectrometer in an actual temperature measurement system in a calibration state, and figuring out a peak wavelength λ m; inputting the first digital distribution spectrum to a single chip or a PC installed with a first physical model for data processing, and carrying out curve fitting on the first digital distribution spectrum by using the least square method to acquire parameters X and X reflecting the energy level structure; acquiring a Wien's displacement law correction formula of the to-be-measured object, and inputting the Wien's displacement law correction formula to the single chip or the PC in the actual temperature measurement system as a second physical model; inputting the verified parameter X reflecting the energy level structure into the second physical model to calibrate the actual temperature measurement system; measuring a second digital distribution spectrum of the emissive power, changing with the wavelength λ, of the to-be-measured object at a to-be-measured temperature by using a digital spectrometer in the actual temperature measurement system in a temperature measurement state, and obtaining a specific data of the peak wavelength λ m; inputting the peak wavelength λ m acquired in the step into the PC or the single chip in the actual temperature measurement system in the temperature measurement state, and carrying out operation processing according to the second physical model to acquire a temperature value of the to-be- measured object; and displaying the temperature value of the to-be- measured object through a display; wherein the first physical model is specifically: a formula formed by adding two energy level structure correction parameters X and X to the Planck formula applicable to the ideal black body: E λ T = X 1 Cλ 1 − 5 e X 2 C 2 λT − 1 − 1 Wherein, E ( λ,T) represents the spectral radiant flux density emitted by a non-black body, and the unit is Wcm -2 ·μm -1; C = 3.741844×10 -12 W·cm -2 is called a first radiation constant; C 2 = 1.438832544cm·K is called a second radiation constant; λ represents the radiation wavelength, and the unit is μm; T represents any known fixed temperature of the to-be-measured object, and the unit is K; X and X represent the energy level structure parameters and are two undetermined parameters added to the Planck formula, and wherein the second physical model is specifically as follows: λT m = X 2 × 2.898 × 10 − 3 m ∗ K. measuring a first digital distribution spectrum of emissive power, changing with a wavelength λ, of a to-be-measured object at an arbitrary known temperature by using a digital spectrometer in an actual temperature measurement system in a calibration state, and figuring out a peak wavelength λ m; inputting the first digital distribution spectrum to a single chip or a PC installed with a first physical model for data processing, and carrying out curve fitting on the first digital distribution spectrum by using the least square method to acquire parameters X and X reflecting the energy level structure; acquiring a Wien's displacement law correction formula of the to-be-measured object, and inputting the Wien's displacement law correction formula to the single chip or the PC in the actual temperature measurement system as a second physical model; inputting the verified parameter X reflecting the energy level structure into the second physical model to calibrate the actual temperature measurement system; measuring a second digital distribution spectrum of the emissive power, changing with the wavelength λ, of the to-be-measured object at a to-be-measured temperature by using a digital spectrometer in the actual temperature measurement system in a temperature measurement state, and obtaining a specific data of the peak wavelength λ m; inputting the peak wavelength λ m acquired in the step into the PC or the single chip in the actual temperature measurement system in the temperature measurement state, and carrying out operation processing according to the second physical model to acquire a temperature value of the to-be- measured object; and displaying the temperature value of the to-be- measured object through a display; wherein the first physical model is specifically: a formula formed by adding two energy level structure correction parameters X and X to the Planck formula applicable to the ideal black body: E λ T = X 1 Cλ 1 − 5 e X 2 C 2 λT − 1 − 1 Wherein, E ( λ,T) represents the spectral radiant flux density emitted by a non-black body, and the unit is Wcm -2 ·μm -1; C = 3.741844×10 -12 W·cm -2 is called a first radiation constant; C 2 = 1.438832544cm·K is called a second radiation constant; λ represents the radiation wavelength, and the unit is μm; T represents any known fixed temperature of the to-be-measured object, and the unit is K; X and X represent the energy level structure parameters and are two undetermined parameters added to the Planck formula, and wherein the second physical model is specifically as follows: λT m = X 2 × 2.898 × 10 − 3 m ∗ K.