Abstract: Variations in the cathodoluminescent properties of the carbonate minerals in reservoir sandstones are usually attributed to differing properties of manganese as the most important activator, and iron as the main inhibitor of luminescence. The results of research on the cathodoluminescence and microprobe analysis in this study led to the following conclusions.(1)The cathodoluminescence will get dark when the carbonate minerals contain FeCO₃ more than 0.04 mol, or MnCO₃ less than 7×10^-5 mol.(2) The higher the ratios of FeCO₃ to MnCO₃, the weaker the cathodoluminescence of the carbonate minerals.(3)The carbonate minerals must be cathodoluminescent when the ratios of FeCO₃ to MnCO₃ are less than 1.(4)The cathodoluminescence tend to disappear when the iron or manganese contents appromaxite to zero.