The present invention relates to the technical field of display, and provides a display substrate and a preparing method thereof which can solve the problem of lower light-emitting efficiency of the display substrate in the prior art. The display substrate of the present invention comprises a plurality of display units of at least two different colors. The display substrate further comprises a plurality of bragg reflection units in different regions corresponding to respective display units, each bragg reflection unit comprises first structural layer and second structural layer which are alternately stacked with each other and have different refractive indexes; thickness of each of the first and second structural layers is ¼n wavelength of incident light from corresponding display unit, wherein n is refractive index of the first or the second structural layer. The display substrate of the present invention has higher light-emitting efficiency and is applicable to full-color display.