One of the challenges or difficulties in translating law texts is the necessity of classifying the terminologies for translators within languages. The notion of finding a classification of law terminologies is to facilitate and have a wide view to improve the quality of translation in the law texts within languages. For this purpose, the researchers of this study comprehended that there was not any classification of law terminologies between English and Persian languages. Primarily the material of this study was selected from some national and international law coursebooks. Then, the researchers intended to explicate a translation model for these two languages in terms of the qualitative design. As a result, by the analysis and comparison of the different theorists’ classifications of translating law terminologies within other languages from the past to the present time, and the researchers’ experiences of teaching legal texts translation within English and Persian languages, the translation of law terminologies of these two languages was classified into five categories through providing examples from the selected law coursebooks as follows: 1) differences in culture-bound concepts of law; 2) different English equivalents for one Persian equivalent; 3) different collocations; 4) faithfulness in transferring the meaning; and 5) transferring the same structure from a language to another. Based on the results, this model of classification can be very essential and useful for translators of such texts, educators in teaching the law text translation, and learners or students attended in ESP or EAP classes or courses.