Objective: The purpose of this study was Designing guideline of developing functional reading texts for mentally retarded students in primary school. Methods: This study is exploratory in both documentary and field took place. 100 parentsand 100 teachers of students with intellectual disability and 20 Professionals Exceptional Children were recruited using multiple cluster sampling and convenience sampling method, respectively.In order to collect the required information, a researcher-made questionnaire was used to gather information. Descriptive statistics (mean and percent) were used for data processing. Results: The results of this study showed that functional reading texts requirements for mentally retarded students includes six components of social skills, self care skills, personal hygiene skills, eating skills, dressed skills and independent life skills. Skills identified in order of importance are placed within the functional reading texts divided to required skills, selective skills and optional skills. Conclusion:The results of this study suggest that the reading texts taught to Slow paced students would be more practical, that is, students would be able to read, understand and apply those texts in daily life and position Social functions, their performance improves in reading.