Private ownership of capitalism is the deep cause to result in the financial crisis. Independent operation, profit chasing and greed of financial capital are the direct causes to result in financial crisis. The intrinsic dual contradiction of merchandise in market economy lurks the possibility of financial crisis, but financial crisis unavoidably comes true to break out because of capitalist private ownership of means of production. However, socialist market economy can keep away from financial crisis for public ownership of the means of production. Financial crisis has broken out again in America and has spread uncontrollably into world crisis, which proves to all over world once again the truth raised by Marx that capitalist periodical economy crises exist and capitalist private ownership must inevitably perish, and which proves to all over world once again that the capitalist governable ideas and modes, both Keynesian and Neo-liberalism, are just concrete prescriptions to manage capitalist market economy, which can not remove truly the crisis of capitalist system except prolonging it. Our country need pay attention to avoiding financial crisis from two aspects of both system and mechanism. Editor: Zhou Miao