||The OCP is traditionally recognized as a phonological constraint which bans the adjacency of two linguistic elements that share some identical phonological properties. This paper adopts an OT approach and shows a sub-type of OCP that is triggered by purely syntactic configurations. Knowing that the OCP can be used as a cooccurrence restriction prohibiting the multiple occurrences of some marked construction, this paper adopts the constraint to prevent the marked branching direction from occurring more than once if the basic word order shows the reversed direction. In Hakka, the basic word order of NP is head-final and left-branching, which gives way to right-branching as the marked configuration to indicate topicalization. It is argued that the syntactic OCP effect is observable when more than one nominal constituent within the so-called multiple embedded relative constructions receive a topicalized interpretation, and thus yielding an ungrammatical pattern where the marked right-branching order occurs at two levels of branching within the tree of NP, which is strictly disallowed by the OCP.