Abstract: Temperature control in a CSTR influences product quality and energy consumption. Cascade PID is difficult to meet tracking accuracy and disturbance rejection requirements under complex working conditions due to its deficient tracking and disturbance rejection ability. This study built a control system based on the heat transfer and reaction models, which could better match actual industrial models. By establishing an extended inner-loop model combined with the inner-loop cooling characteristics of the CSTR, an improved offset-free MPC method was proposed with Kalman filter for estimating the states and disturbances. Contrast experiments showed that the proposed Offset-free MPC method exhibited obvious improvement in temperature tracking accuracy and robustness compared to cascade PID. The conclusion of this paper provides a reference for temperature control of a CSTR under actual disturbance environment.