The normal grain growth in volume-conserved two-phase nanocrystalline materials is studied using a modified Potts model, in which the grain boundary migration is driven by the interfacial energy between two phases and the grain boundary energy inside each phase. Monte Carlo simulation results show that the grain growth of one phase is constrained by the presence of the other phase. The power-law grain growth kinetics with an almost temperature-independent exponent of 0.16±0.01 (0.5 in a pure single-phase system) is predicted for two immiscible phases, which is in agreement with experimental observations.