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.