In order to explore the degradation ability of sulfate radical on azo dyes, direct acid resistant red 4BS (hereinafter referred to as red 4BS) was used as a simulated pollutant. The effects of initial c (PDS), Fe (II)/EDTA (molar ratio), and inorganic salt anions on the degradation of red 4BS were investigated through a UV/Fe (II) - EDTA/PDS (PDS is sodium persulfate) system. The results showed that the decolorization rate of red 4BS increased with the increase of initial c (PDS), When c (PDS) exceeds 15 mmol/L, there is no significant change. The best effect is achieved when the Fe (II)/EDTA ratio is 5:1, and the decolorization rate of 0.0380 mmol/L bright red 4BS reaches 93.6% at 5 minutes. The reaction follows a second-order kinetic model. Inorganic salt anions such as HCO3-, Cl -, NO3-, SO42- exhibit significant inhibitory effects on production. Under 100 mmol/L conditions, the decolorization rate of c (inorganic salt anions) decreases by 66.9%, 13.2%, 12.1%, and 9.43%, respectively. By using UV visible spectroscopy, Based on the relationship between its structure and characteristic absorption, it is preliminarily speculated that the pathway of free radical ions in the degradation of bright red 4BS is the first destruction of the benzene ring, followed by the cleavage of the azo bond and the cracking of the naphthalene ring. Studies have shown that UV light can effectively strengthen the activation of perovsulfate by Fe (II) - EDTA to form SO4- · radicals, which has good decolorization ability for azo dyes. The optimal reaction conditions are [PDS: Fe (II): EDTA (molar ratio 15:5:1)], The decolorization rate of Dahong 4BS is as high as 98.1% at 10 minutes