The invention relates to a method of improving the homing and engraftment rate of hematopoietic stem cells and a reagent of the method. By taking small molecule peptides as a main component to performpretreatment on the hematopoietic stem cells, the method provided by the invention improves the homing and engraftment rate of the hematopoietic stem cells in vivo, shortens the time required for reconstruction of a hematopoietic system, improves the success rate of hematopoietic stem cell transplantation and makes up for the status quo of insufficient sources of the hematopoietic stem cells. Inaddition, low-dose intravenous infusion of the small molecule peptides does not have bad influence on the safety of a human body. Thus, the invention actually provides application of the small molecule peptides in preparing a drug for treating diseases of a blood system.