Single-chain Fv (scFv) antibody library against SIEA (soluble immature egg antigen) of Schistosoma japonicum was constructed by phage display technology. Specific SIEA26～28 ku scFv was obtained by screening the SIEA scFv library using the natural molecular candidate vaccine, SIEA26～28 ku. The specific scFv fragment was subcloned to prokaryotic expression vector PET32a and induced the expression of soluble specific scFv in high level. Subsequently, specific scFv as a probe was used to screen the cercaria cDNA library of Schistosoma japonicum to get the coding genes of SIEA26～28 ku molecules. Results showed that specific SIEA26～28 ku scFv with high level expression was achieved. The corresponding gene, ribosomal protein S4 was obtained by initially screening the cercaria cDNA library with the specific SIEA26～28 ku scFv. The obtaining of specific SIEA26～28 ku scFv lays the foundation for further screening and identification of the coding genes of SIEA26～28 ku, the natural molecular candidate vaccine against schistosomiasis.