A simple spectrofluorimetric method was developed for determination of trace amount of adenosine disodium triphosphate (ATP). Under the optimum conditions, we studied the interaction between CIP-Y3+-ATP complex by using absorption and fluorescence spectra. It was observed that ATP remarkably enhanced the fluorescence intensity of the CIP-Y3+ complex at λem=415 nm and the enhanced fluorescence intensity of Y3+ ion remained proportional to the concentration of ATP. The developed method was successfully applied for the determination of ATP in ATP injection sample. A suitable mechanism of fluorescence enhancement between CIP-Y3+ and the CIP-Y3+-ATP system was proposed and discussed.