Growth hormone releasing peptide (GHRP) was synthesized.It is an exogenous hormone promoting pituitary to release growth hormone.The amino acid sequence of GHRP is His-D-Trp-Ala-D-Phe-Lys-NH₂.The synthesis was carried out with SPPS and Boc strategy.The amino acid composition was found in agreement with its caculated values. The purity was 97.7%.The bioassays showed that it enhanced the growth of young mice significantly and this effect depends on the dosage of injection. GHRP is more sensitive to the younger mice.