In this paper, we described assumptions, the standardization, and other generalizations that we used to develop SDS-ALT plans with bivariates. And a method is provided for finding a non-degenerate optimal bivariate SDS-AL T scheme. The important technical steps for finding optimum (or compromise) bivariate SDS-ALT scheme are described. We obtained a two-factor step-down-stress accelerated life test of a two-factor non-interactive model and can decompose the optimal solution of degradation into a non-degraded optimal (or compromise) test scheme.