“…For incompressible MHD equations, many problems have been investigated including the blow-up criterion, the uniqueness of weak solutions and the well-posedness of the smooth solutions, and for more details, see [7,8,9,10,15,16,21,39,40] and the references therein. On the other hand, there are also many results regarding the global existence of the solutions and the decay of the smooth solutions to the compressible MHD equations, see [23,24,28,35]. It is well known that the study for optimal decay rates of the solutions to the fluid dynamics equations is interesting in mathematical analysis.…”