The invention discloses a method for quickly calculating the dominant wavelength in the measurement of colorimetric parameters of a light-emitting diode (LED), which consists of a sectionalized judgment algorithm and a variable step size inquiry algorithm. The method is to acquire relative spectral energy distribution curve data P(lambda[i]) of the LED to be measured through a sensitimeter (CCD) of a spectrograph, calculate the chromaticity coordinate of the LED according to the color matching function of CIE 19312 degree *(lambda), *(lambda), *(lambda), take equal-energy white light WE(xe=0.3333, ye=0.3333) as a reference light source, sectionalize data with the wavelength range between 360 and 780 nanometers in a CIE1931 chromaticity diagram, judge the section with the dominant wavelength according to the chromaticity coordinate, and quickly calculate the dominant wavelength of radiant light of the LED to be measured by the variable step size inquiry algorithm, wherein the precision is 1 nanometer. The method reduces the calculation of the dominant wavelength, improves the working efficiency, and is used for the online measurement and the separation of the colorimetric parameters of the LED.