A color temperature conversion system and a method thereof are capable of converting the color temperature to the color temperature almost identical with the color temperature obtained by the Robertson algorithm. The color temperature conversion system has an XYZ conversion unit for converting an RGB signal of input video data into an XYZ value in a CIE coordinate system, a chroma calculating unit for calculating X and Y coordinate values of a pixel corresponding to the converted XYZ value, an offset compensate unit for compensating the X coordinate value calculated by the chroma calculating unit based on an X coordinate value difference and a Y coordinate value difference of a color temperature on a white point line of the CIE coordinate system and an actual color temperature of the video data, in the case the color temperature is calculated based on the calculated X coordinate value, a color temperature calculating unit for calculating the color temperature of the video data that is inputted based on the compensated X coordinate value, and a color temperature conversion unit for converting the color temperature calculated by the color temperature calculating unit into a predetermined color temperature and outputting the converted predetermined color temperature.