In this paper, we investigate the time-periodic solution to a coupled compressible Navier–Stokes/Allen–Cahn system which describes the motion of a mixture of two viscous compressible fluids with a time periodic extal force in a periodic domain in RN . The existence of the time-periodic solution to the system is established by using an approach of parabolic regularization and combining with the topology degree theory, and then the uniqueness of the period solution is obtained under some smallness and symmetry assumptions on the extal force.