Abstract: Academic production mostly relies on external sources have been published used by the researcher in order to support his ideas, opinions and the results that may be reached by. And so the use of external sources is acceptable automatically but what is unacceptable is the failure of the researcher mentioning those sources which leads to plagiarism. The plagiarism is stealing the ideas of others and a violation where the university take it seriously in all cases. The best way to avoid plagiarism is rewriting texts that quoted from another source in a way that allows writing it of a new form as well asthe reference to the sources this so-called paraphrasing. In this study, we have a way to detect the paraphrasing used on the texts as well as determine the percentage to disclose the amount of the change on the texts. Results proved that the researcher is to paraphrase the texts taken from other sources at different rates of which exceeded 45% including good paraphrasing by typing text in a new way in addition to changing the words sites but some are very simple change in meaning and location.