Tryptophan is one kind of representative pollutants in waste water. The present paper focuses on the research on the relation between the consistence, pH, ionic strength and the fluorescent characteristic of tryptophan. The result shows that: (1) Tryptophan in the low consistence range (0.01-3 m·L-1) shows good linear relation, the correlation coefficient is up to 0.995 88, while the linear relation in the high consistence range (3-30 mg·L-1) is slightly worse and the correlation coefficient is only 0.942 24; (2) In the acidic condition, the relative fluorescence intensity of tryptophan strengthens while the pH arises, and when the pH is in the range (6.5, 7.5), the intensity is relatively steady, while when the pH reaches 12, it drops off; (3) With the enhancement of the ionic strength, the relative fluorescence intensity of tryptophan reduces to some extent, and when the nitrate ion reaches to a high consistence, the spectrogram shows EERS.