Language is a means of acquaintance in societies (groups). This linguistic process begins from listening and in its written form it becomes a reading process. Reading and writing are two main properties of education system. Writing is a complex linguistic process and active as well, that’s why it is required to analyze student’s linguistic mistakes. This study under the title (Illustration and Linguistic Analysis of Basic Senior’s Writing Mistakes) attempts to analyze basic senior’s writing mistakes and it classifies these mistakes as well, I have applied descriptive approach in undertaking this study. I have used statistic methodology for identifying such mistakes. The study concluded that majority of basic senior’s writing mistakes are linguistic mistakes, a rate of 73% of such mistakes are committed on the morphological level of words, and 27% is the rate regarding the mistakes related to listening, which means: it comes on the top of the list of such mistakes. Regarding the mistakes related to the kind of teacher and dictation the rate is 24% which means it occupies the second place on the list