Abstract: In this paper,the potentiometric titration curves of 26 drugs and recoveries weremeasured by using coated carbon PVC membrane electrode as indicating electrode and standard solutionof sodium tetraphenylboron as titrant.These curves were calculated by the parameter methtod and thesuperiority sequence was evaluated. The results show that the superiority sequence of the poten-tiometric titration curves depends on the structure of the cations of the drugs,1.0×10^-5mol·L^-1 ofthe drugs can be measured for methylene blue, berberine , cyproheptadine and benzhexol;1.0×10-4mol·L^-1 for diphenhydramine and aconitine;1.0×10-3 mol·L^-1 for brucine,tetramisol,chlorphe-namine maleate and procaine;5.0×10-3mol·L^-1 for ketamine,vitamin B6 and vitamin B₁; andwhen ionized by iedomethane,1.0×10-5mol·L^-1 for clotrimazole,1.0×10-3 mol·L^-1 forthiamazole , atropine and physostigmine;5.0×10-3mol·L^-1 for amidopyrine and imidazole.