Abstract. One of the most important parts of oil contracts is the financial regime. The terms of financial regime are proprietary and governed based on negotiation between parties, and they play a significant role in the success of the contracts and the parties’ consent. In this article, the nature and structure of the financial system are presented in the buyback contract and the new oil contract of Iran. Then, by reviewing the literature ‎ related to the financial system and interviewing the experts, it has been decided to choose criteria for assessment of financing. In order to compare the evaluation criteria for prioritization, as well as to choose the best financing method in the buyback contract‎ and the new oil contract of Iran, the experts’ opinions and TOPSIS decision-making method were used. According to the results of TOPSIS method, the criteria of foreign investment attraction and financing, onservative production of oil, logical flexibility in the description, and costs of contractors’ duties are of the highest priority in the financial system of the two contracts, and based on the introduced criteria, the IPC contract was identified as a suitable contract for the Iranian oil industry.