In this paper, we adopt optimality theory to describe some important properties of postpositions. First, they follow the complement in their own projections. Second, they select either an NP or a PrepP as the complement, but they do not select another PostP as the complement to avoid the adjacency of two postpositions. Third, when occurring in a VP, they precede the head verb if they are complements of verbs and follow the verb if they are adjuncts. Fourth, the insertion of de between a postposition and its complement is prohibited. Fifth, postpositional stranding is disallowed. As will be shown in this paper, by using OT as the theoretical framework, we establish a theoretical model that is able to account for the syntactic properties, configurations, and restrictions involving the category of postpositions. Finally, this paper provided a brief cross-linguistic generalization of syntactic properties related to postposition between Mandarin Chinese and English from the perspective of OT.
