An ultrasound-assisted situ oxidation process has been demonstrated for the Cr(VI) adsorption experiment with PPy, PPy/Fe3O4 and PPy/Fe3O4/AgCl composite in a relatively wide pH range. The PPy, PPy/Fe3O4 and PPy/Fe3O4/AgCl composite were characterized with XRD, SEM, TEM and VSM measurements, and were further tested in the role of Cr(VI) adsorption in aqueous solution. Up to 100 % adsorption was found with 500 or 1000 mg L−1 Cr(VI) aqueous solution at pH 3.0. Adsorption results showed that Cr(VI) removal efficiency by PPy, PPy/Fe3O4 and PPy/Fe3O4/AgCl decreased with an increase in pH. Compared with contact time (30 min) of PPy and PPy/Fe3O4 adsorbent, 15 min adsorption of PPy/Fe3O4/AgCl composite can almost reached the adsorption equilibrium. The kinetics of Cr(VI) adsorption with PPy, PPy/Fe3O4 and PPy/Fe3O4/AgCl follow the pseudo-second-order model. The eco-friendly PPy/Fe3O4/AgCl featured with magnetism and excellent reusability offers a promising adsorbent material for Cr(VI) contaminated water.