A study on the fluorimetric reaction of Al-H2QS-CTMAB and conditions of the determination of aluminium in water by model 930 fluorimeter is reported. A good linear relationship between the strength of fluorescence and aluminum concentrations, ranging from 0 to 1.5 micrograms/10ml, is observed. Interferences from other constituents in water can be eliminated by the masking effect of 1, 10-phenanthroline and hydroxylamine hydrochloride and by using standard addition method. The coefficient of variation and recovery vary from 2.9% to 8.9% and from 87% to 105%, respectively. The detection limit is 3 x 10(-2) micrograms/ml. This method is rapid, sensitive, accurate and suitable for the determination of contents of aluminum in drinking and natural waters.