Fiber identification is a necessary basic task for the conservation of paper-made relics, ancient books and documents, and is of great importance in making conservation plans and selecting repair materials. Calcium oxalate crystals are common ergastic substances in plants, and their forms are much related to the categories of plants. In this study, calcium oxalate crystals in the fibers of traditional handmade paper were observed using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectrometry, X-ray diffraction (XRD), scanning electron microscopy (SEM),optical microscopy (OM) and polarized light microscopy (PLM), to characterize calcium oxalate crystals in each kind of paper. Furthermore, the possibilities of adding the polymorphism of calcium oxalate crystals to the fiber identification system are also discussed as a means of improving the methodology of fiber identification.