Sulfate reducing sludge (SRS) was employed as the raw biomass material and pyrolysed at 500oC under oxygen-limited condition, for the functional biochar preparation (i.e. SBC-500). With the anaerobic sludge (derived from sludge thickening tank in a sewage treatment plant)-based biochar (i.e. BC-500) as the control, both materials were characterized by SEM, XRD, FTIR and BET. The environmental application of them for Cr(Ⅵ) removal was also evaluated and compared. The results showed that the SBC-500 is superior to BC-500 in terms of biochar yield, ash content and pore volume. As for BET analysis, BETSBC-500 was 17.9 m2/g, significantly larger than BC-500 (10.24 m2/g). According to the SEM results, porous structure was clearly displayed in the surface of biochar. And irregular marginal crystal structure were embedded in the biochar. The presences of graphene carbon and FeS crystal and amorphous carbon were confirmed in SBC-500 via XRD analysis. The FTIR spectrum presented the anti-symmetric stretching peak of O═S═O and the characteristic absorption peak of S═O bond in the SBC-500. The Cr (Ⅵ) removal efficiency by SBC-500 (via adsorption and reduction) could achieve 100% after 48 hour’s reaction, at pH 3, 0.2 g dosage and Cr (Ⅵ) initial concentration of 10 mg/L. With the initial concentration increased to 200 mg/L, the adsorption capacity of Cr(Ⅵ) was 8.22 mg Cr(Ⅵ)/g by SBC-500. The results of this study may provide new concept and insight into the economical disposal of the surplus sludge and the effective remediation of heavy metal polluted water body.