This research is based on showing the personality of Al-Mamoons which was characteriseal by education and acquiring more knowledge affecting his internal and external policy. At early of his age, Al-Mamoon had been taught religion. This lasted for many years. Then he studied scholastic theology until Al-Mu'ta/ila succeeded to conivince him to accept their policy and doctrine. Al-Mamoon studied pure scientific subjects like, engineering, philosophy and logic. He paid homage to the eighth Imam of Al-Shiites to rule the country after him. This shows the effect of Al-Mutazila on the personality of Al-Mamoon they prefer Ali Mahamuods cosin on other Prophets companies.They found that he was the only one to rule after the prophet (Mohmmad). AL-Ma'moon had followed the doctrine of Mu'tazila (the problem of creating Qura'n). AL-Mamoon was peaceful in his religious trends and ideas.On the other side, his external policy, Al-Mamoon declared that he was ready to sign a long-term treaty with the Byzantiums provided that the emperor should send (Lio) the mathematician scientists to Baghdad to lecture there but this was not achieved because the imperor refused. AL-Ma'moon position was no more than a reflection of his desire to study science and knowledge.