The Holy Quran, which is a fundamental axis for establishing rules and reforming Arabic styles, has many translations and interpretations, which are a source for learning about the source language and the subject of the original text, as well as the grammatical and rhetorical rules of this book. Moreover, mastering the original language and familiarity with its complex secrets by translators greatly contributes to the success of providing an accurate and smooth translation. One of the Quranic symbols is the use of the letter Lam with different meanings. In this article, researchers attempt to study and analyze the letter Lam through the descriptive analytical method, which is of interest to many interpreters, translators, and Arabic speakers. While studying the translation of the preposition in some contemporary Persian translations of the Quran (Makarim, Meshkini, Karmaroudi, Fouladvand, Moezzi, Saffarzadeh), researchers will criticize and evaluate them, and after mentioning the strengths and weaknesses of each, the most important way to translate the letter Lam will be discussed. The result showed that in translating the letter Laam, translators used four types of translation: 1- Literal translation 2- Literal translation with an interpretative addition 3- Conceptual translation 4- Conceptual with an interpretative addition. It is very important for the translator of the Holy Quran to be familiar with literary and interpretative topics and the types of translation of Laam al-Jar, as this familiarity will help the translator avoid misunderstanding and incorrect translation of Quranic verses.