The thermal decomposition behavior of the ingredients , RDX、NC、NG、and NQ in nitramine propellants RGC and RCGU were experimentally studied. The results show that the crook of these propellants burning curves were caused by the difference of thermal decomposition behavior between the solid filler RDX and NC-NG double-base binder. Because of its individual thermal decomposition behavior, NQ could be used to regulate the above said difference and straighten the burning rate curve.