A powerful technique using the simultaneous solution method is proposed to calculate the steady state gain which is quite essential to the synthesis of process control structure. After calculation of the solution of variables in process design, the steady state gain can be calculated accurately from the partial matrix of the inverse Jacobian matrix which is available for the solution. This technique is more effcient than the technique employing the conven-tional sequential modular approach which requires repetitive calculations to obtain the steady state gain. This method was applied to a typical binary distillation column to illustrate its usefulness in finding the feasible control structures for the top and bottom concentration control.