In this Research, the effect of private speech training on executive function of boys between 9 to 11 years old in Isfahan City was examined. This research is an experimental study of pre-test/post-test with control groups. It had a two-stage sampling. Final sample included 20 attention deficit boys (10 for experiment group and 10 for first control group) and 9 normal boys for second control group. Instruments used in this research included British Picture Vocabulary scale, Short form of Wechsler's Intelligence Scale for Children- Revised, Tower subtest of NEPSY Neuropsychology test. To analyze private speech of children, their speech were videotaped while solving Tower subtest and Videos were content analyzed by three encoders. Results showed that children with attention deficit, had significantly more errors in compare to first and second control groups; while both experiment and second control group (which both had been trained) had significantly more amount of private speech in compare to first control group- which had not trained. According to the findings of the research, it can be concluded although  private speech training can increase the amount of  private speech produced by attention deficit children, this increase in speech,  not only will not necessarily increase function of children, but it may backfire on difficult tasks.