Abstract: AIMTo study a continuous, on-line and automatic monitoring method for dissolution of drugs. METHODSA new fiber optical chemical sensor prepared by sol-gel immobilization of molecular probe was reported. Based on multiple quenching of flurescence, an instrument and software system was designed to on-line monitor the drug dissolution of rifampicin. RESULTSThe concentration of rifampicin was linear with ln(F₀/F) when concentration was in the range of 10～170 μg·mL^-1. The relative coefficient was 0.9993. The procession of dissolution can be on-line monitored. Parameters were obtained directly from the dissolution curve. There is no distinctly difference when compared with the method of the Pharmacopoeia of People's Republic of China (P>0.05). CONCLUSIONThis procession analysis can reflect the real dissolution of drug and obtain the total information.