Abstract: This paper summarizes the basic principles of flow injection chemiluminescence（FICL） by literature review, identifying its five key technical features: rapid analysis, high precision, automation, low noise, and low cost. The experimental process for determining catechol using this method was also analyzed. The results show that adding silver nanoparticles（AgNPs） to a luminol-potassium ferricyanide chemiluminescence system enhances the luminescence intensity. The linear range for catechol detection was determined to be between 5.0×10^-5 mg/L and 1.0×10^-2 mg/L, with a detection limit of 4.8×10^-5 mg/L. The relative standard deviation for 11 consecutive measurements of 8.0×10^-4 mg/L catechol was only 2.3%. This indicates that the method can meet the high-precision detection requirements for catechol in environmental water samples and confirms its applicability in water environment monitoring.