Nano zero valent iron (nZVI) has long been used as an effective reductant for the treatment of a wide array of environmental contaminants including halogenated organic compounds, nitro aromatic compounds, arsenic, nitrate, azo dyes, and heavy mental ions. However, major challenges still remain unresolved for field applications of nZVI. High-energy mechanical ball milling (BM) is an easy-to-operate, low-cost and efficient solid-state powder processing technique. No studies have been reported about the preparation of ball milled nZVI-biochar and mechanism on the effectiveness of Cr(VI) removal by ball milled nZVI-biochar have been investigated. A novel Fe0@biochar was synthesized by ball milling method for the first time and tested for Cr(VI) removal in aqueous solution. FTIR, SEM, TEM, XRD was used to characterize the properties of the composite. Longer ball milling time and acidic condition were favorable for Cr(VI) removal. Biochar pyrolysis temperature had a significant impact on Cr(VI) removal, and removal efficiency improved from 49.6% to 97.8% when pyrolysis temperature varied from 300℃ to 700℃. Graphene structure in biochar at higher pyrolysis temperature acting as electron conductor promoted electron transfer from Fe0 to Cr(VI). The main removal mechanisms were adsorption by functional groups, electrostatic interaction and subsequently reduction. Ball mill could depassivate the Fe0@biochar for its regeneration on Cr(VI) removal. Comparing with traditional preparation method for Fe0@biochar, ball milling avoided the contamination of chemicals and the preparation conditions were easy to realize, which is environmental friendly and economic. The composite could also be regenerated by ball milling after several cycles of usage. Therefore, the ball milled Fe0@biochar composite had a promised prospect in field application as reactive barrier for ground water remediation.