In LED products, an important specification number is color temperature, which is related to the color characteristics of LED lighting products. General lamps also have color temperature specifications. The measurement unit of color temperature is Kelvin scale, that is, K. at the beginning, it was observed by Kjeldahl in the iron and steel plant that when the dissolved metal began to reach the maximum temperature, the metal showed different colors when it was shining. Then it was recorded in data units. Later, the standard table of LED color temperature was generated.

The definition of color temperature was expressed by absolute temperature K, that is, the standard blackbody was heated. When the temperature rises to a certain extent, the color of the blackbody begins to change from dark red to light red to orange yellow to white blue, and then gradually changes, we call the absolute temperature of the blackbody as the color temperature of the light source.