In view of the solid propellant aging which influences the performance of long storing solid rocket engine, the main factors of the solid propellant aging are discussed and the solid propellant aging mechanism is analyzed from the influence of the component of solid propellant, environment humidity and storing temperature. Then the methods of predicting solid propellant aging study are analyzed and reviewed, and the emphasis is put on analyzing the methods of mechanical properties, activation energy, gel content, Fourier infrared spectrum analysis and dynamic mechanical analysis. And simultaneously the main content of these methods and the reliability of these results are analyzed. Finally the developing trend of solid propellant aging is prospected from investigating the mechanism of solid propellant aging and the application of modern analysis equipment.