Abstract: The results of comparative study showed that the perfusion pressure of cerebral blood vessels and the blood pressure of femoral artery were lowered by both cyclandelate( I ) and nicotinoyl cyclandelate( Ⅱ )given intravenously in anaesthetized dogs. The hypotensive action of Ⅱwas stronger than that of I at lower doses (1mg/kg, 3mg/kg) , but the maximal effect of Ⅱat higher dose (6mg/kg) was not as active as that of I. The volume flow of coronary system wag significantly increased by both I and Ⅱin isolated rabbit heart,l and Ⅱalso could antagonize the BaC12 induced constraction of coronary vessel. The spasmodic action of Ach on isolated guinea—pig ileum was decreased by I and Ⅱ.The effect of I was more potent.However, the toxicity of Ⅱ was less than I when given intravenously.