In order to solve the online monitoring problem of remote monitoring system LED in railway monitoring equipment, the main features of RGB color space and color sensor were analyzed, TCS34725 was used to measure color components in RGB color space, white balance algorithm was used to convert RGB to HSL,to solve the problem that the measured colors had different results under different lighting conditions. Finally, by measuring the color of transparent objects at different distances, the experimental results show that the errors are small and the color can be measured.