The complementary DNA (cDNA) plasmid libraries of adult worm, metacercariae and egg of Clonorchis sinensis (C. sinensis) were constructed for researches on genomics and proteomics of C. sinensis. The full-length cDNA sequence encoding tegumental protein 31.8 kDa (CsTP31.8) was identified from the adult cDNA library. The cDNA sequence has been submitted to the GeneBank Database with accession number ABK60086. This novel cDNA sequence contains 828 bp with a putative open reading frame of 275 amino acids. The deduced amino acid sequence shows identity to membrane-associate antigens or tegumental antigens of other species. There were conserved calcium-binding EF hand and dynein light chain type 1 in the sequence. CsTP31.8 transcripts were detected in cDNA libraries of adult worm and metacercariae but not in that of egg. Recombinant CsTP31.8 was expressed and purified from Escherichia coli BL21 (DE3). CsTP31.8 was immunolocalized at the tegument of adult C. sinensis by using antirecombinant CsTP31.8 sera.