Under the circumstances of global economic unbalance and excess liquidity，the oil price is experiencing a new upward cycle.Benifiting from oil price upward，Middle East oil exporters engendered abundance petrodollars and resulted in inner assets rising suddenly and sharply.The directions and purposes of petrodollars have influential effect to global economy.Petrodollars were saved up largely so that reduced aggregate demand and induced unbalance of global economy.The future trend of U.S Dollar and the prevailing speculative capital under the excess liquidity will both enhance the uncertainty of future global oil market，what’s more，the challenges faced by oil-dollar pricemaking mechanism and finance turbulence induced by Sub-prime Loan Crisis also indicate the upward risks of global oil market.