Abstract:3D Slicer, a useful Medical Image Processing Platform to research medical image, has obtained the attention of researchers worldwide. This platform has many advantages such as free and open source, high scalability, good portability etc. In this paper, 3D Slicer's GUI is analyzed and divided into three parts: the core, the command-line modules and the Python scripted modules. In order to achieve the goal of internationalization, QT's internationalization method is also researched in this paper according to different parts. Beside, the internationalization of input of 3D Slicer was also accomplished by analyzing the encoding of the input strings.