Objective: The aim of this research was investigated effectiveness of constant and variable practice on acquisition retention and transfer of motor skills in intellectual disability.  Method: In this quasi experimental study, 23 boys with age 8-12 according to IQ (50-70) were randomly selected and participants were assigned after pre-test and a training session according to obtain score, age and IQ in two groups homogenous. These subjects were practice 3 sessions and each session 40 throw. Data using two-way analysis of variance with repeated measures were analyzed. Results:  results showed in Stage retention in two group in throwing increased accuracy (p<0/044) and variability decreased (p<0/07). Results showed in stage transfer variable practice group succeed in transfer skill to new qualification. Also variable practice group have little variability (p<0/006) and much accuracy (p< 0/02) than constant practice group. Conclusion: According to the finding this research variable practice group was capable retention and transfer skill to new situations and also rules regarding schema Schmidt confirmed in people with intellectual disability.