First‐principles calculations and thermodynamics analyses were combined to study the surface stabilities of 3C–SiC and H2O adsorption on the (110) surface. The stoichiometric (110) surface was predicted to be generally the most stable. Only at the extremely C‐poor condition, the nonstoichiometric Si‐terminated (100) could become more energetically favored. The adsorption and dissociation of single H2O molecule on the 3C–SiC (110) were then comparatively investigated. Calculations show that H2O molecules prefer to partially dissociate into one hydroxyl OH and one H adsorbed at the top‐most Si and C sites, respectively, leading to the formation of a hydrogen network on the surface. The calculated equilibrium adsorption diagram further suggested that the 3C–SiC (110) surface can be only either completely clean or fully covered by the partially dissociated species of H2O, for a wide range of temperature and the partial potential of H2O.