Model predictive control(MPC)

as an advanced control strategy

has been widely applied to process industry.But the soft constrain limits of MPC is often set in a conservative way in industrial application

which leads to poor economic performance.For MPC system

the quadratic economic performance index is used to assess the economic performance in the paper.After that the problem of solving the optimal solution is transformed into a typical linear programming problem with constraints.Then according to the historical data and optimal operation results obtained from quadratic economic performance function

evidential network modeling of multivariable MPC can be built.Through reasoning and decision-making

the reason which causes the system performance decline can be got.The strategy to improve the control system performance is proposed.Finally

the effectiveness of assessment economic performance based on evidential network is verified through the simulation experiments.