A new fluorescence spectrophotometric method has been studied for the determination of trace germanium with phenylfluorone.It is found that at the presence of CTMAB,in the buffer solution of pH=5.1 HAc NaAc,phenylfluorone forms micelle complex with germanium.The fluorescence intensity of phenylfluorone was increased.But it was unstable.When acidity of system is up to 0.3mol/L,the fluorescence is stable and the sensitivity is higher.The excitation wavelength and the emission wavelength is 477nm and 525nm respectively.The detecion limits of germanium is up to 0.05μg/L.The range of determination for germanium is 0.2~2.0μg/L.The relative standard variation of 13 determination of 0.5μg/L germanium was 6%.The average recoveries of germanium added to sample were in the range of 95%~110%.The method has applied to the determination of germanium in flyash sample with satisfactory results.