Private sector investment, particularly foreign investment is a major and vital category in exploration and development of oil and gas industry. Since the major oil fields are in undeveloped countries, which most important feature of them is government budget lack and weak domestic private sector financing, attracting foreign investment is important. Absence or lack of them has created some problems. Production sharing agreement is, in the last-mentioned countries, as tools for attracting of foreign investment from overseas. Due to the international popularities of the PSA and discussions on design a new contract patterns, in this paper, the use of PSA in the upstream oil industries of Iran is discussed. In this talk, with the use of descriptive and analytical methods and refer to authentic sources of oil law, have studied by financial & non-financial terms of PSA and then, comparing its efficiency in analogy with buy back, analyzed. Finally, this result was obtained that using of PSA in analogy with buy back, will some benefits to our Countries.