Abstract: The paper focuses on analyzing Jerome Model and Horace Model to interpret the criterion of translation: faithfulness. Jerome model firstly emphasizes word-to-word equivalence, later holds that the translation strategy is based on the translator flexibly, while Horace model requires that it needs to be faithful to the customer through negotiation. Considering the times and translation practice of Jerome and Horace, translation, a kind of social practice, can not be separated from the needs of social recognition, and it needs adjusting with the change of society. Therefore translation criterion: faithfulness, is not absolute, eternal and unchangeable, but relative, dynamical and historical.