Abstract: Based on sequential bound unconstrained minimization method of the nonlinear constraints,the sequential bound constrained minimization method(SBCMM) of steady-state optimization of large-scale process systems is studied.After applying relaxation variables to the engineering model,the penalty function of SBCMM only contains the penalty items about equality constraints but not the the ones about bound or inequality constraints.The solution of the original problem is obtained by solving a series of bound constrained minimization sub-problems but not by unconstrained minimization sub-problems.Finally,SBCMM is tested by a scale-variable nonlinear programming problem and an optimal control problem.The numerical results show that SBCMM is applicable to optimization solution of large-scale process systems and has the stability and effectiveness.