Representing a class of languages through operations on its subclasses is a traditional issue within formal language theory. Among the variety of representation theorems for context-free languages, Chomsky-Schützenberger theorem is unique in that it consists of Dyck languages, regular languages, and simple operations. In this work, we obtain some characterizations and representation theorems of context-free languages and regular languages in Chomsky hierarchy by insertion systems, strictly locally testable languages, and morphisms in the framework of Chomsky-Schützenberger theorem.