Abstract: Currently, in situ chemical oxidation (ISCO) is commonly used to treat chlorinated solvents in contaminated soils and groundwater. Using potassium permanganate (KMnO₄) in ISCO to treat the chlorohydrocarbon in contaminated groundwater has been proved effective and practicable, but the manganese dioxide (MnO₂) precipitate generated in the reaction could affect the treatment to be efficacy and extend the remediation time. The co-effects of sodium hexametaphosphate (HMP) and sodium dodecyl sulfonate (SDS) on PCE oxidation performance by KMnO_4were investigated in aqueous solution. Batch experimental results showed that the ionic strength (I) had a significant effect on the MnO_2precipitate, and the MnO_2precipitate generated faster with the increase of I. Under the experimental conditions temperature 20℃, ρ(PCE) 20mg/L, KMnO₄/PCE molar ratio 15∶1and ionic strength 0.1mol/L, using HMP alone could reduce the MnO_2precipitate. There was no MnO_2precipitate in 24h with ρ(HMP) of 0.1g/L. Using SDS alone could increase the production of Cl^-. The production of Cl^- increased by 8.2% with ρ(SDS) of 1.0g/L, while the generation rate of MnO_2precipitate increased greatly. With the combination of HMP (ρ(HMP)0.1g/L) and SDS (ρ(SDS)1.0g/L), the production of Cl^- increased by 7.5% and there was no MnO_2precipitate during 24h reaction. The testing results strongly suggested that the combination of HMP and SDS can improve the removal rate of PCE and can alleviate the occurrence of the MnO_2precipitate.