The theory of schema in the

Critique of Pure Reason

is one of the difficulties in the study of Kant’s theoretical philosophy. One limitation of related studies is that they do not unify the schema of pure concepts of the understanding （transcendental schema） and those of sensible concepts （empirical schema）. This paper provides a systematic interpretation of the two types of schemas. First， due to the heterogeneity of categories and phenomena， categories need to be mediat

ed by a transcendental time-determination or time-schema before they can be applied to phenomena. The time-schema makes it possible to recognize objects in general. Second， although the objects of sensible concepts have images and thereby are homogeneous with phenomena， they require some kind of schema in order to obtain a universal representation. The schema of sensible concepts is empirical and constitutes the framework in which concrete experiential objects are constructed. Finally， the transcendental schema and the empirical schema are products of the pure a priori imagination （transcendental imagination） at different levels， and together they constitute the mechanism by which the objects of knowledge are made possible.