Almost all the countries, including China, have paid more attention to the shadow banking system as the financial crises happened in 2008 because of subprime mortgage crisis. At the same time, the monetary policy transmission mechanism is changed when the shadow banking system develops rapidly, and the effect of monetary policy is weakened accordingly. Taking measures and strengthening regulation are in need urgently. The paper analyses the related subjects including the present situation, size, features, active and negative influence of the shadow banking system in a normalized way, and some suggestions are provided correspondingly