With due attention to the oil position of Iran economy, investigating the reasons of changes in oil price and modeling to predict its fluctuations has always been one of the most important domains in study of Iran economy literature. With the expansion of oil stock and oil futures market, oil market and then theory of price expectations changed formation of crude oil price. So in short term, with changes in interest rate in effect of monetary policy, liquidity flows between financial markets (money, bond, capital) and oil market, crude oil price deviates from its long-term path. This paper examines the deviation of crude oil price form its long-term path with regard to the relationship between mentioned markets in short-term which mainly are due to monetary policy. For this purpose, Fisher price model and Samuelson theorem are tested by use of time series data of 2005-2013 AD and Garch model test. The results show that the effect of changing in interest rate on crude oil index ( Dubai, Oman and Brent) is negative. Also, the effect of changing of stock market capitalization on this crude oil price is positive. The main reasons for negative impact of rising interest rates are increase of maintenance costs, storage of crude oil and as a result they caused to reduced demand in cash market. Also, positive impact of changes in capital market because of industrial developments, which can lead to increase demand for crude oil in market, can be explained