Abstract: The rule of full stress is an efficient method in the optimal designfor statically indeterminate shape steel truss. But the major shortcomingof this method is that the convergent speed is very slow. In this paper, a new area ratio method for the optimal designbased on full stress is proposed on the basis of ``the direct method ofstability design for shape steel columns'', in which the convergent speed ofrepeated calculations is greatly improved, and the design cost iseffectively reduced.