Schistosomiasis threatens thousands of millions of peoples' health every year in the world. Schistosoma japonicum, a pathogen of schistosomiasis, is covered by a lipid bilayer membrane which plays an important role in nutrient transport, signal transduction, interaction with host's immune system, etc. Thus, molecules in the tegumental membrane have gained more and more interest for understanding biological and pathological processes of schistosoma. In this study, we found a protein from S. japonicum cDNA library which has a 20.8 KDa molecular weight (SjTP20.8). Recombinant SjTP20.8 was produced and purified from Escherichia coli. The recombinant protein could be detected by S. japonicum-infected mice and human sera, and it had been found localizing in the tegumental membrane of S. japonicum in the section using immunofluorescence assay. In electrophoretic mobility shift assay, the protein could bind calcium iron in neutral condition. Result of cercariae challenge experiment indicates antibody against this protein can protect mice from chronic hepatic fibrosis. Our results indicate the S. japonicum tegumental protein 20.8 is crucial for the parasite's calcium absorbing and reproduction.