It was found that 20 amino acids could inhibit the intensity of the luminol-H_2O_2-CuSO_4 chemiluminescence system.Using this character,a rapid and sensitive method for the determination of 20 amino acids was developed with flow injection coupled with chemiluminescence detection.Under the optimal conditions,the detection limits of 20 amino acids were in the range of 4.5×10~(-7)- 4.3×10~(-10) mol/L,and the relative standard deviations were less than 3.2%.The proposed method was successfully applied to drug analysis.The possible mechanism was also discussed. It was found that 20 amino acids could inhibit the intensity of the luminol-H 2 O 2-CuSO 4 chemiluminescence system. Using this character, a rapid and sensitive method for the determination of 20 amino acids was developed with flow injection coupled with chemiluminescence detection. Unit the optimal conditions, the detection limits of 20 amino acids were in the range of 4.5 × 10 -7 -4 4.3 × 10 -10 mol / L, and the relative standard deviations were less than 3.2%. The proposed method was successfully applied to drug analysis. The possible mechanism was also discussed.