The structural and chemical properties of iron oxides are usually pertinent to the high affinity of silicon and iron in the environment, which further influences the retention of As. Previous work mainly focused on the Fe-Si interactions in Si-rich environments, while there is a dearth of both structural alteration of iron oxide in low-silicate conditions and the mechanistic understanding on the adsorption As process in Si-Fe oxide (Si-FeOOH). Herein, we investigated the adsorption of As on Si-FeOOH, proceeding from the physical and chemical properties of low-silicate co-precipitated β-FeOOH. Additionally, the effect of initial concentration of arsenic, oxygen, pH, and electrolyte concentration were discussed. SEM, TEM, XPS, FTIR, XRD and Rietveld refinement, BET and Zeta potential were used to characterize the structure and surface properties of Si-FeOOH; atomic fluorescence spectrometer were used to determine the residual As solution. DFT-calculated adsorption energies and electron localization function distribution for (310) facet is consistent with the analytical results obtained from experiments, demonstrating that the little dopped silicate stabilized the crystal microstructure of β-FeOOH, and strengthened the combination of As by generating the intramolecular hydrogen bonding and promoting electron transfer.