The merit of internal model control(IMC) is that the influence of disturbance can be depressed in the lowest range. During operation, unmodeled dynamics and parameter variations may severely infringe the IMC performance. TheH8‐control theory with a weighting function can attenuate the influence of system perturbation. In this paper, we combine the characteristics of IMC andH8control, and offer a control structure to discuss the robustness problems. The development is based on employing a state‐space approach to treat optimization problems rather than using the conventional complex variable approach. The performance of the proposed control structure is illustrated through a specific chemical reactor system. The simulation results show that the proposed structure indeed overcomes the disadvantage of IMC. Moreover, it can obtain a better control performance than the conventionalH8control.