A ruler surface structure for clear marks display in a dim light mainly comprises a ruler surface and a brightening layer. The ruler surface is marked with marks which are characters or lines. The brightening layer is laid on the marks to enhance the display and identification effect of the marks. By using the different light sensitivities formed by the brightening layer on the marks and the other regions of the ruler surface, including the functions of light reflection or luminescence, the marks can be clearly displayed and identified in the dim light.