Abstract: In this paper the medical CT images were used as research objects, and we researched on the application of moment invariant features in medical CT images. First, the nature of the moment invariant features insensitive to rotation, translation and scale was verified through experiments. Next, we took the content-based medical image retrieval for example, revealed the principles of the application of moment invariant features in content-based medical image retrieval. Finally, the using occasions of the feature extraction method based on moment invariants were analyzed. The experimental results play an important role in promoting the application of moment invariant features in medical image recognition, image matching, shape analysis, image segmentation, content-based image retrieval and etc.