Based on gallic acid ester (PG) of Fenton reagent oxidation solid green fade has obvious inhibitory effect principle, A new method of determination of PG in food was established using spectrophotometric method. The influence of the solid green consumption and other factors on the system were studied, the experimental conditions were optimized . In selected experimental conditions, the method of linear regression equation for delta rho △A625nm=59.328ρ+0.008 5，the correlation coefficient (R2) of 0.995 2, the linear range of 8.3×10-4~1.6×10-2 mg/mL, detection limit of 9.8×10-5 mg/mL. Method used in the determination of food in PG, the determination results of RSD was 3.4%, the recovery in 96.25%~103.3%.