Color proportion and color temperature in RGB laser display are studied based on CIE1931 and CIE1964 standard colormetric observers to realize the automatic white balance of laser projection. Firstly, the color coordinates and color temperature of white color generated by RGB colors are described based on Grassmann′s laws of color mixture. Secondly, the laser power ratios of red laser (638 nm), green laser (532 nm, 525 nm) and blue laser (445 nm) are calculated at 6500 K and 9300 K, and the change of power ratio is analyzed with continuously adjustable temperature of 6500-9300 K. Then, the influence of green wavelength change on color temperature and luminance, and the change of color temperature caused by power degradation are gained. Finally, an experimental system for measuring color temperature of laser display source is set up, and the experimental result of color temperature is lower about 15% than the theoretical color temperature according to the standard power ratio.