Aim: The aim of the study is to consider the effect of Sina educational instrument on reading accuracy of educable mentally retarded students. Method: This study is experimental pretest – posttest design with control groups. Statistical universe included all educational mentally retarded studying in 3-5 elementary grade in Boujnurd city .the samples include 28(14 and 14 with subject in control) selected after considering of interring criteria. The sample consist of 28 (14 in experimental and 14 in control) selected considering internal criteria. Results: the means of marks in experimental group in teams of substitutions, wrong pronunciation, Omission of a letter and word, addition and Transmission were lower than in control group (p< . /05) but in items addition of a letter and word, and correctional repeat there was not any statistically significant difference (p>. /05).Conclusion: The use of Sina educational instrument was effective on reading accuracy of educable mentally retarded students.