Nowadays, errors made by language learners are not seen as signs of language incompetency, rather than are considered as measures for assessing second language , competency in learning a second language. In the present research, it is attempted to analyze the written errors of Kazakh- Persian students based on Corder’s model. The main question of the study is the determination of frequent errors in the writing of Kazakh students, and the hypothesis is that the grammatical errors are more than lexical errors in the written text of the Kazakh language students. The present research is descriptive-analytic and its theoretical framework is the proposed Corder model. The statistical population of this research is non-Persian speaking Kazakh who study Persian language as a second language in Persian language at the Ablai Khan University in Kazakhstan. The research tool is a collection of 24 written articles from Kazakh undergraduate students that relates to the final test of their writing course with the right to choose a topic from among the five suggested subjects. On average, each entry contains 150 words. First, the language errors of Kazakh students were identified and extracted based on the proposed Corder model. Then, based on the type of errors, they were categorized and analyzed using statistical software. The frequency of errors were determined and finally analyzed. The research findings confirmed the hypothesis. The results of this research show that out of a total of 466 errors identified in the Kazakh written articles, the most errors are due to the non-observance of grammatical points with 231 cases and 47% of the total errors, and then the graphological – phonological errors with 182 cases and 41% of The sum of the errors is the worst mistake. Lexico-semantic errors with 43 occurrences and 10% of the total errors, in the next rank are the frequency of errors, and the lowest errors with 10 occurrences and 2% errors, are related to the cognitive- application errors.