Direct conversion of biomass-derived syngas (bio-syngas) to dimethyl ether (DME) at pilot-scale (100t/a) was carried out via pyrolysis/gasification of corncob. The yield rate of raw bio-syngas was 40–45Nm 3 /h with less than 20mg/Nm 3 of tar content when the feedrate of dried corncob was 45–50kg/h. After absorption of O 2 , S, Cl by a series of absorbers and partial removal of CO 2 by the pressure-swing adsorption (PSA) unit sequentially, the obtained bio-syngas (H 2 /CO≈1) was directly synthesized to DME over Cu/Zn/Al/HZSM-5 catalyst in the fixed-bed tubular reactor. CO conversion and DME space-time yield (STY) were 67.7% and 281.2kg/m cat 3 /h respectively at 260°C, 4.3MPa and 3000h −1 (GHSV, syngas hourly space velocity). Synthesis performance would be increased if the tail gas (H 2 /CO>2) was recycled to the reactor when GHSV was 650–3000h −1 .