Abstract: A new method was studied for the determination of phenazinone in nutrient solution by HPLC. An Aichrom Bond-AQ C₁₈ column was used with a mobile phase consisted of mixture of methanol /water (40∶60) at a flow rate of 1.0 mL/min, and UV detector wavelength was 315 nm. The method offered good linearity 1.0~200 mg/L (r=0.9996). The recovery was in the range of 96.0%~99.0%, RSD was 0.20%. The detection limit was 0.02 mg/L .The method was simple, accurate and rapid reproducible and can be used for quality control of phenazinone.