In this study, we report the desirable conversion of H2O2 to % OH with aquifer sediment activated by ascorbic acid. Although aquifer sediment contained various iron minerals, such as goethite, hematite, montmorillonite, muscovite, chlorite and phlogopite, it could not efficiently activate H2O2 to produce % OH. Interestingly, the presence of ascorbic acid dramatically promoted the % OH conversion efficiency of H2O2 by aquifer sediment to remediate organic contaminants in groundwater, which was ascribed to the efficient iron cycle of aquifer sediment induced by ascorbic acid. Among these minerals in sediment, goethite and hematite were more reactive than other minerals to activate H2O2 in the presence of ascorbic acid. Although the initial pH could affect the % OH conversion efficiency of H2O2, H2O2 could be decomposed by aquifer sediment at pH 3-11 after the introduction of ascorbic acid. Along with the complete degradation of organic contaminants, the final pH of solution increased to 8.3, which was close to the initial pH (8.9) of groundwater. Moreover, packed column of aquifer sediment could also catalyze the H2O2 conversion to % OH for the removal of different organic contaminants with adding ascorbic acid, suggesting a new strategy for in situ chemical oxidation remediation of organic contaminated groundwater.