Ontologies, as the fundamental building blocks for the Semantic Web, are the highest-level classification scheme in the family of Knowledge Organization Systems (KOS). With the emergence of big data, ontologies are one of the keys to unraveling the information explosion problems. Under the big data situation, many language cultures are in a pressing need to construct ontologies. Cross-lingual ontology research has thus become a pivotal concern in this global age. Researchers worldwide try to be interoperable with ontologies written not only in English, but also in other languages. Yet, constructing a cross-lingual ontology can be difficult, and a detailed mapping method is often hard to find. The purpose of this study is to establish a feasible practice on building cross-lingual ontologies. The study will focus on the construction of an English-Chinese ontology from an existing source ontology and a KOS source. This study will also address the synonymy and polysemy problems of the target language (Traditional Chinese).