Abstract: The R-spondin （Rspo） protein family is a newly found secretory protein family in recent years which include four family members （Rspol to Rspo 4）. All the members in Rspo protein family contain four highly conserved domains： hydrophilic secretion signal peptide domain in N-terminal, two or three furin-like cysteine-rich domains, thrombospondin-type 1 （TSP1） domain and amino acid-rich basic domain in C-terminal. Wnt signaling pathway is one of the significant pathways in organism which plays a crucial role in the process of growth and development. As a member of Rspo protein family, Rspol is a potential female-determination factor that can activate Wnt signaling pathway and regulate the sex-determination and other biological function of organism by cooperation with Wnt ligands.