Abstract: For searching more effective antiarrhythmic agents, on the basis of integration of the structural feature of certain potassium channel blockers available, various acylamino groups were introduced to the position 4 of the benzyl ring of this series of compounds. Thus, eight 1-(4-acylamino)benzyl-1,2,3,4-tetrahydroisoquinolines were designed and synthesized, which had not been reported in the literatures. Compounds V₁,V2 and V₆ at concentration 10^-6 mol·L^-1 depressed rat aortia contraction induced by high KCl (80 mmol·L^-1). The effect was similar to that of tetrandrine. Compound V₆ showed potent antiarrhythmic activity at the dosage of 1 mg·kg^-1.