Abstract: A new kind of all - solid- state electrochemical detector for very toxicalkaloids such as aconitine, mesaconitine and hypaconitine has been studied. It exhibitsNernstian response for these alkaloids with a slope of 56 mV/decade over the concentrationrange of 3×10^-5 ～1 ×10^-2mol/L at pH 2 ～7 under the flow condition. Directpotentiometry for the determination of aconitine in Aconitum kusnezoffii Reichb.,Aconitum carmichaeli Debx. and Xiaohuoluo Wan showed average recoveries of 98.5, 98.3and 96.8% and relative standard deviations of 1.8, 2.4 and 3.5%, respectively. It can beused for the determination of very toxic alkaloids in the above mentioned samples by flowinjection analysis. It also can be used for the study of the hydrolytic kinetics of aconitine.