In this paper, a new Co/ZrO2-SiO2 catalyst with specific bimodal structure was developed and applied for jet fuel direct synthesis from syngas in Fischer-Tropsch synthesis (FTS) with varied 1-olefins as additives. In a slurry-phase reaction process, 1-olefins as additives were introduced into reaction system to enhance the selectivity of jet-fuel-like hydrocarbons (C-8-C-16), at the same time suppressing the formation of light hydrocarbons including CH4 and CO2. The new FTS reactions, due to the co-fed 1-olefins, showed anti-Anderson-Schulz-Flory (anti-ASF) law product distribution. Among all the co-fed mixed 1-olefins, 1-decene and 1-tetradecene mixed with the volume ratio of 1:1, exhibited the highest selectivity of jet-fuel-like hydrocarbons. This new Co/ZrO2-SiO2 bimodal catalyst had specific bimodal structure, which realized its excellent catalytic performances in the FTS reaction, because the large pores provided efficient pathways for reactants and products diffusion, and high metal dispersion was obtained by the newly formed small pores with enhanced active surface area. (C) 2016 Elsevier Ltd. All rights reserved.