Aim: Immunoglobulin D (IgD) has remained a mysterious antibody class.Recent research shows that serum IgD level changes significantly in some autoimmune diseases.Secreted IgD (sIgD) can bind to a putative IgD receptor (IgD-R) on CD4+ T cells and may induce abnormal T cell differentiation.This study aimed to construct recombinant hgD-Fc protein to competitive inhibition IgD binding with IgDR.Methods: Human IgD-Fc sequence was amplified by RT-PCR and then subcloned into pET28a(+) empty vector.After prokaryotic expression through escherichiacoli, we obtained the recombinant hIgD-Fc protein by affinity chromatograph.Western blot was used to identify the recombinant hIgD-Fc protein.Human peripheral blood monouclear cells (PBMC) proliferation were detected by CCK8 method.Results: We obtained stable and active recombinant hIgD-Fc protein.And the recombinant IgD-Fc protein can downregulate human IgD protein promoting proliferation effect in human PBMC.Conclusion: This result suggests that the recombinant IgD-Fc protein may competitively inhibit IgDs function and may play an therapeutic role in autoimmune diseases.