Scientific cognition of paper relics is the key to the conservation of this kind of precious cultural heritage. In this study, four widely used traditional Chinese handmade papers, including bamboo paper, hemp paper, mulberry paper and kozo paper, were analyzed using pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The results show that a higher content of phenolic compounds were detected in bamboo paper, macromolecular triterpenoids such as β-amyrin, α-amyrin and stigmastan-3,5-diene were discovered in mulberry paper and kozo paper, but these special compounds were not found in hemp paper. These pyrolysis products can be used to distinguish hemp paper, bamboo paper and bark fiber papers (mulberry paper and kozo paper). The methods and results were applied in the scientific cognition of a pair of Qing Dynasty waxed-paper couplets:1) to confirm that the fiber raw material for the waxed paper was a mixture of mulberry and straw fibers; 2) to detect a large amount of long-chain fatty acids and alcohols which indicated that the presence of beeswax; 3) to detect pyrrole substances which proved that animal glue was used as the cementing material for mounting; 4) to detect biological alkali substances, which indicated the use of vegetable dyes. The study shows that the Py-GC/MS method could not only determine the paper fiber source of traditional Chinese paper relics, but also identify the waxing, cementing and dyeing information on paper relics. The type of bark paper fiber was identified in combination with the traditional Herzberg staining method. This information provides a scientific basis for the conservation and restoration of paper relics. Moreover, this study provides new ideas for the scientific cognition of paper relics.