Introduction: Studies have shown despite the difficulty inphonological awareness skills among those children with Down syndrome they can grow these skills. The aim of this study was to design of training program of awareness from phoneme and study of its impact on skills improvement of awareness from phoneme among children with Down syndrome.
 Materials & methods: In this single case study with A-B-A examine, eight students were selected among student with down syndrom in the first grade by available nonprobability sampling. After designing of training program of awareness from phoneme and use of personal information questionnaire, Goodenough draw-a-man IQ test and phonological awareness test, 36 sessions of 30 minutes was held for each subject that intervention was ended when it reach the criterion of 80% of correct answer in the generalize items. Data were analyzed by visual analysis method and determine of effect size.
 Findings: Finding showed that effect size of intervention was high in increasing of awareness from phoneme skills in all six subjects. Also according to visual analysis, subjects operation increased after intervention. This improvement was faster in phoneme blending skill and in phoneme isolation skill was slower than other skills. Minimum effect size was observed in phoneme isolation skill and maximum effect size in phoneme blending skill.
 Discussion & Conclusion: Designed program have a positive effect on phonemic awareness skills in student with Down syndrome and this program will enhance their skills.