This paper makes an effort to investigate the obstacles in nonequivalence at the idiomatic and expressional level and then presents some certain factors to face such difficulties in "Animal Farm" novel (1945) by George Orwell and its translation by Amir Amirshahi (1969). The researchers in the current study try by analyzing six certain strategies as using an idiomatic expression of similar meaning and form, similar meaning but dissimilar form, borrowing the source language, translation by paraphrase, translation by the omission of a play on idiomatic expression and translation by the omission of entire idiomatic expression (Baker, 2011). Moreover, the present research is a descriptive, non-judgmental, comparative and corpus-based analysis of English-Persian parallel study. The findings demonstrate the fact that the practical ways in the translation of idiomatic expressions presented by Baker (2011) are applicable, and the most useable strategy is using an idiomatic expression of similar meaning but dissimilar form at 35.96%.