With the death of Prophet Muhammad (S.A.W) the enemies of Islam had started their intrigues to create obstacles against the fast growing and spreading message of Islam or Quran and Sunnah. In eighth century the Christian missionaries were seriously apprehended from the great successes and victories of the Muslim in European countries. They, thus, tried their best to oppose Islam and Muhammad (S.A.W) through their unscientific and polemical writings (e.g. the writings of Johan of Demascus) and their military or warlike activities (e.g. long-duration Crusades of 11th to 13th centuries). But they did not succeed to destroy the Muslims and Islam in medieval times. In the 17th and 18'1' century, the period of renaissance, the trend of scientific study on Sirah from original sources started but could not promote with true spirit of seeking real knowledge. During this period, thus, a dangerous Orientalism had taken place, which caused British and French Colonialism and afterwards the imperialism. This confrontation between the East (especially the Muslims or Arab countries) and the West continued and aggravated even in 20th century when America appeared on the map of the world. Now, beyond any doubt, the Orientalism was definitely meant for seeking of knowledge of the Islamic sciences and of Muslim countries for the purpose of gaining power, domination and possessions of Muslim countries and their economic resources especially the oil-resources of the Arab world. The most important Orientalists promoting the power-based scholarship are Huntington, Bernard Lewis, Berger, Fukuyama etc. The pure scientific era of research i.e. the 20th century was expected to give the right direction to the Orientalists' research on Sirah. But, the works of the Orientalists are still creating the hatred and enmity between the two civilizations such as the tricky and dangerous works of W. Montgomery Watt have been serving the same purpose. Although, he presents an attractive rhetoric in his works but the medieval style of unscientific research is still continuing in the form of modern scientific research which does not provide objective study but a purely religiously biased study on Sirah. This dissertation aims at contributing towards scientific point of view and to review the studies by the Orientalists.