An automated flow-batch analyzer (FBA) based on spectrophotometry was developed for the determination of nitrite (NO₂^-) in environmental waters. The FBA consists of a homemade flow cell, light source, detector and a mini-syringe pump, which was controlled by self-designed software written in LabVIEW. Two LEDs and a light-to-voltage converter were used as the light source and detector respectively. The chemical detection method was based on spectrophotometry and modified Griess reaction. With the optimized conditions, the limit of detection (LOD) was 0.018 μmol·L^-1 and the relative standard deviations (RSDs) at different concentrations (0—12 μmol·L^-1) were 0.54%—3.63% (n=3). Measurements of different aqueous samples (n=21) showed no significant difference between results obtained by developed FBA and a commercial spectrophotometer.