A novel MILP model for plantwide multiperiod optimization of byproduct gas supply system in the iron- and steel-making process is proposed. Compared with the previous optimization model, proposed approach simultaneously optimizes the byproduct gasholder levels and gas distribution among conflicting objectives. Both integer and continuous variables are used in determining the optimal fuel load change according to the fuel types. Objectives include the minimization of the unfavorable byproduct gas emission or shortage, oil consumption, the number of turn on/off of the burner, maintaining the normal holder levels, and maximizing fuel usage efficiency. Case study results show that the proposed model finds the optimal solution in terms of total cost reduction and the different optimization model structure makes the solution more applicable than the previous approach.