This paper combines the order of infinitesimality with the limiting form of comparing discriminant methods for a positive term series under the model of MOOC. A proper “reference series” is found by equivalent（or same order）infinitesimality with original series, or highorder or loworder infinitesimality respectively which general term corresponds to. The problem of fragmentization and knowledge systematicness of the comparing discriminant methods for a positive term series is solved. Moreovr, the effectivity of this method is illustrated by some instances in discriminating the convergence of infinite series.