We propose a mathematical model described in a bilinear partial differential equation of nonlinear coupled with state variable and control variable in this study. Furthermore, we propose the optimal servo system design of the stochastic model considering the disturbance. The general mixing reaction system is described in a bilinear partial differential equation.The complete mixing reaction system is assumed to maintain a space uniformly, we construct a bilinear model lumped parameter system. The target model is linearized by using a exact linear theory, we present a design proposal on the optimal servo system considering a disturbance into the system
