Abstract: The present invention relates to a novel stimulating factor which can promote the growth of hematopoietic stem progenitor cells and vascular endothelial cells, i.e. hemangiopoietin (HAPO), characterized in that design a variety of primers based on known sequences, obtain a series of gene segments through PCR amplification, clone into prokaryotic expression vector using double-enzyme restrict sites, in which two fragments of 879 bp and 558 bp were expressed in engineered bacterium, HAPO of 31.8 KD and 20.1 KD (292 and 186 amino acids) were obtained through enzyme digestion, specific antibodies were obtained after purification and immunizing rabbit with it, the antibodies is a useful tool for clinical diagnosis and treatment of haemopoietic and vascular diseases.