The luminance and line width of HUD symbols are important for the display performance of a HUD.The symbol characteristics determine the visibility and comfort level in observation under all-weather environment including high intensity light of the outside and dark of the night.The emission spectrum time characteristics luminance distribution line width and other characteristics of the HUD were analyzed and tested.The analysis shows that:1) The HUD symbol is 20 ms cycle pulsed light and the luminance presents Gaussian distribution; and 2) The symbol display luminance of a HUD varies with eye box position and field angle.This article provides a theoretical basis for improvement of the symbol characteristics and test of the symbol display luminance and line width.