Carbonation leads to the decrease of alkalinity of concrete, which seriously harms the durability of reinforced concrete structures. In this paper, Na2SiO3, NaOH and Na2CO3 were used as alkali activators, and the influences of the types of alkali activators and Na2O equivalent on the carbonation resistance of single-component alkali-activated nickel slag cement mortar were investigated. The results show that, when the Na2O equivalent is the same, the carbonation resistance of single-component alkali-activated nickel slag cement mortar is the best in the single doping of NaOH samples, and the carbonation resistance is the worst in the single doping of Na2SiO3 samples. Na2CO3 partial substitution for Na2SiO3 can improve the carbonation resistance of cement mortar samples, while the effect of Na2CO3 partial substitution for NaOH on the carbonation resistance of cement mortar specimens is related to the Na2O equivalent. With the increase of Na2O equivalent, the carbonation resistance of single doping of Na2SiO3 and mixed doping of Na2SiO3&Na2CO3(3∶1) samples increases first and then decreases. The carbonation resistance of single doping of NaOH samples increases continuously in the early stage, and increases first and then decreases in the later stage. The carbonation resistance of mixed with NaOH&Na2CO3 (3∶1) samples improves in the early stage, but decreases in the later stage.