Stiff ordinary differential equation results in certain system models in which both alow and fast dynamic phenomena are present. The singular perturbation theory ( SPT) was extensively used to study a certain class of stiff systems, in which some ‘ parasitic ’ elements are present. This paper makes use of the advantage of the single term Walsh series method which is A-stable, to optimize this class of systems. A numerical example is considered and the gains are compared with actual vulues.