This research specifically addresses the influence of the phenomenon of linguistic interference of the primary language, Arabic, on the written production of FFL learners, at the Department of French, university of Mosul. We adopt nominal and verbal sentences. According to our subject, linguistic interference is a strong phenomenon that exists in student-written sentences at all levels of grammar. The analysis of the writing of the learners is the only thing this study deals with. The objective is to pinpoint the question of linguistic interference that occurs when the source language and the syntax structure of foreign languages overlap, particularly in student writing. This research makes an effort to determine the distinctions and parallels between the two languages. The goal is to enhance students' understanding of syntactic structures and minimize mistakes made. This research tries to improve learners' understanding of both languages' syntactic structures, which will help them overcome any difficulties in learning and teaching situations.