Co2C is considered to be the active phase for the formations of C2+ species (C2+ oxygenates and hydrocarbons) and CH4 in Fischer-Tropsch synthesis (FTS), in this study, the mainly exposed (1 0 1) surface is employed to investigate the effects of C- and Co-termination Co2C surfaces on FTS selectivity (C2 species and CH4); here, the density functional theory calculations are carried out. The results show that on the C-Co2C(1 0 1) surface, CH3 is the main form of CHx species, CH4 formed by CH3 hydrogenation is the main C1 species; then, CH3CH2 formed by CH2 coupling with CH3 is the main C2 species; however, the formation of C1 species CH4 is more favorable in kinetics than that of C2 species CH3CH2. Whereas on the Co-Co2C(1 0 1) surface, CH is the main form of CHx species, C2H2 formed by CH self-coupling is the main C2 species, CH4 formation is very difficult. For the C2 species formation, both C- and Co-Co2C(1 0 1) surfaces prefer to form the hydrocarbons rather than the oxygenates. Thus, either the C- or Co-termination Co2C(1 0 1) surface is in favor of hydrocarbons formation (CH4 and C2+ hydrocarbons), the surface termination of Co2C(1 0 1) surface affects the product selectivity of FTS reactions, and the exposed Co-terminated surface prefers to form C2+ hydrocarbons. As a result, adjusting the surface termination of Co2C catalysts can tune the selectivity of FTS reactions.