The simulations of the influence of temperature on Cr atom substitution character in Ni-Cr-Al alloy were performed based on microscopic phase-field model. It is found that nonstoicheometric ordering L12 phases appear first with congruent ordering+spinodal decomposition mechanism, then followed by non-classical nucleation and growth mechanism with the rising of aging temperature, and the incubation period increases gradually at 873~1173 K. The volume fraction of L12 phases increases and that of D022 phases decreases. D022 phases disappear and only L12 phases are remained at 1173 K.