This paper describes pre-processing phase of ontology graph generation system from Punjabi text documents of different domains. This research paper focuses on pre-processing of Punjabi text documents. Pre-processing is structured representation of the input text. Pre-processing of ontology graph generation includes allowing input restrictions to the text, removal of special symbols and punctuation marks, removal of duplicate terms, removal of stop words, extract terms by matching input terms with dictionary and gazetteer lists terms.