In this paper we consider boiler-turbineâs nonlinear dynamics and linearize the nonlinear parts based on the piecewise affine method in order to obtain a mixed logical dynamical model of the system. By using piecewise affine approach for linearization of the systemâs nonlinear equations, the obtained linearized model switches between different modes based on its parameters, so acquired piecewise affine model can be categorized in the switching hybrid system class. We model the linearized boiler-turbine system in a mixed logical dynamical model of the hybrid systems using hybrid systemâs description language and hybrid toolbox. Mixed logical dynamical model describes system by two linear equations and one linear inequality with a reasonable accuracy and considering the constraints in the system. We provide a comparison between the acquired mixed logical dynamical model using piecewise affine linearization method and the actual boiler-turbine system through simulation and show the efficiency of the mixed logical dynamical model to describe the Boiler-Turbine system.