There exist two different strategies in model predictive control (MPC), i.e.，set-point control and zone control. In comparison, zone MPC is thought to be a better strategy. However, there exists an improved set-point control strategy, i.e.，double-layered MPC, which computes set points through the steady-state target calculation in the same control cycle. In this paper, from the aspect of process steady state, the principles of zone control and double-layered MPC are analyzed. We discuss the differences and similarities between the two strategies both qualitatively and quantitatively, and prove that the two strategies are consistent in a certain context. Simulation results are given to validate the conclusion.