Abstract: SP-6 was synthesized by solid phase method in 95%purity on HPLC, The dataobtained from amino acid analysis and fast atom bombardment were in good agreement with theoretical values。In travenous injection of Sp-6 in rabtrits at the dosage of 14.3μg/kg,resulted in blood pressurereduction of 4.4 kPa,i.e. 34%(P<0.001).When the concentration of SP-6 in Tyrode solutionwas 5.2× 10^-4mg/ml the contraction of rabbit duedenum longitudinal muscle increased by 105%.(P< 001).When the concentration was more than 1×10^-3mg/ml, the contractile effect wasrestrained significantly,Dropping 30μg of SP-6(1×10^-3mg/ml)to toad intestinum tenue mesenteri-ale in situ, the mesentery arterioles were expanded by 30%.