The chromatographic behaviours of about two hundred of drugs were investigated under reversed-phase condition using methanoI-water system of more than 40 different pH values as elucnts. The capacity factors of these drugs were measured on several ODS columns. In terms of the characterization of retention values as function of the mobile phase pH ?the drugs were divided into three classes ： basic.acidic and neutral. The elution order reversal was frequently encountered with basic drugs within pH4～5. The database program was written by using the languages of Foxbnse +2.1 and of Foxpro 2.5 for windows.The databases and the classification might play important roles in the recognition of the trends of chromatographic behaviour of these drugs and the determination of initial chromatographic condition and reduce analysis time and efforts.It may help us to obtain the optical separation results ano to select the best internal standards.