Abstract: Corn straw is one of the major crop straws considered for producing renewable fuels and energy in China. Production of densified biomass fuel (DBF) and biogas from corn straw are two main conversion approaches. One of the major problems associated with the DBF production from corn straw is rapid wear of the briquetting/pelleting unit. The primary technical barrier for anaerobic fermentation of corn straw is its recalcitrance structure. Aiming at these problems, we proposed a process of DBF production from corn straw pretreated by anaerobic fermentation. In this process, corn straw is firstly anaerobicly digested to produce biogas, and then the solid digestate is pressed into DBF. In order to prove the feasibility of this process, the anaerobic fermentation experiments were performed at 38℃ at 12% of total solid (TS). The experiments were divided into two groups with a digestion period of 10 and 20 days, respectively. After anaerobic digestion, the digestate was shed, dried, and pressed into DBF with a diameter of 10mm in a hydraulic device at pressure up to 6 MPa and a temperature of 100℃. The anaerobic experimental results showed that after 10 and 20 days of anaerobic fermentation, 14.49% and 32.01% of the energy contained by corn straw was converted to biogas energy, and the characteristics of digestate were beneficial to DBF production in terms of lignin and extract contents. The lignin content of solid digestate was elevated to 16.98% and 17.92%, and increased by 24.4% and 31.3% compared to 13.65% of corn straw.