Scanning Electron Microscope (SEM) has been widely used in the observation of surface and cross section of materials. So it is important to prepare the cross section of various specimens. In this study, a novel cross section preparation method using argon ion beam (called argon ion beam cross-section polisher or CP) was introduced. This method can not only overcome the problem of artifacts caused by mechanical polishing on the polished surface, but also enable one to prepare a wider area of specimens than the Focused Ion Beam (FIB) method. The soft materials, composite materials with different hardness, multilayer films and powders were all easily polished with few artifacts using this method.