The invention belongs to the biomass energy utilization technology field, and discloses a cobalt-based Fischer-Tropsch fixed bed catalyst used for biomass synthetic gas and a preparation method therefor. The catalyst is composed of the following materials, by weight, 5-15% of Co3O4, CuO with a content of being more than 0 and less than or equal to 5%, 0.1-1% of RuO2, 3-20% of ZrO2, and the balance being gamma-aluminum oxide. The preparation method is as follows: first, gamma-aluminum oxide with a BET specific area of 180-210 m<2> / g and an average pore size of 14-16 nm is weighed according to required weight, the gamma-aluminum is peptized with 1-3wt% of concentrated nitric acid, then 0.5-2wt% of a pore forming agent CMC and 0.5-2wt% of auxiliary extruding agent sesbania powder are added, after the above mixture is mixed, pinched, ground and agglomerated, strip extrusion molding is carried out, after drying and calcinations, an alumina carrier is obtained; second, ZrO2 component is loaded through a saturation impregnation method, and a catalyst carrier is obtained after drying and calcination; third, Co3O4, CuO and RuO2 components are loaded through a saturation impregnation method, and a catalyst is obtained after drying and calcination. The catalyst has high CO hydrogenation catalytic activity and C<+5> selectivity, and low CH4 and CO2 selectivity.