One way to understand the importance and nature of a great revolution as Islamic Revolution of Iran is through comparing that with other revolutions in the world. Considering political situation, international support, and military and economic condition of that time, this essay tries to make a comparison between Islamic Revolution and four great revolutions: 1789 of France, 1917 of Russia, 1949 of China, and 1962 of Algeria. The comparison shows that contrary to those four countries, the-1979-Iran, or better to say Pahlavi Regime, was in a good shape considering the economy, international support and military conditions. However, legitimacy and acceptability of all these four governments and Iran of that time was not popularly in good condition.