Certain samples, which are of pre-cambrian metamorphic rocks in China (Hebei Province and Inner Mongolia etc.), post-cambrian metamorphic rocks in Tibet and other areas, as well as granitic rocks with different ages and genesis, have been observed by means of CL (cathodoluminescence). CL related to certain concentrations of the transition elements, may reveal textures in rocks and show indirectly the characteristics of chemical composition of minerals. This paper deals with the application of CL to the studying of metamorphic and granitic rocks as follows; 1) determing metamorphic grade indirectly, 2) revealing the palimpsest structures of primary rocks, 3) identifying finegrained and luminescent mineral, 4) studying mineral reactions, 5)reconstructing deforma tionstructures.