Abstract: The synthesis of methanol from CO2- rich syngas derived from biomass was carried out in a high pressure micro-reactor system. The effect of temperature, pressure and space velocity on space time yield (STY) and concentration of methanol was studied using a feed gas with H2 (52.5%), CO (21.5%), CO2 (22.8%) and N2 (3.2%). The results show that both STY and concentration of methanol increase with temperature and reaches maximum at 260 ℃, and then decreases. Higher pressure results in higher STY and concentration of methanol. STY increases and methanol concentration decreases under higher space velocity. The STY is 0.79 g·mL-1h-1 and methanol concentration is 96.2% under the conditions of 4 MPa, 260 ℃ and 5 280 h-1. Compared with the results of methanol synthesis using CO-rich industrial syngas, the STY and concentration of methanol decreases by 25.8% and 1.64% respectively. In order to improve efficiency of the whole system, off-gas can be used to produce electricity.