Abstract: In order to detect the quality of the cartridge precisely in real-time, it is needed to acquire the X ray photo of the cartridge by Non Destructive Testing(NDT) method, then some preprocess algorithms are used to enhance the signal to noise ratio (SNR) of the image. The local average minimum algorithm and the local smoothness minimum algorithm are proposed to extract the feature parameters of the cartridge, which are compared with the normal cartridge parameter, and an identification report about the cartridge quality will be given. The method is fast, precise and efficient.