As the most important antigen present cells in the processes of post-transplant complications in vivo, dendritic cells (DCs) play an important role in graft versus host disease (GVHD), infection, and relapse. DCs have became one of the most critical problems in the transplantation immune research recently. The reconstitution kinetics of circulating DCs after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and its relationship with the post-transplant complications, even the promoter or inhibitor affecting this process are summarized in this review.