With an increasing tendency of the natural disasters frequency and intensity in China,risk analysis of design flood in Yangtze river for the Three Gorges Dam Project (TGP) should be of paramount importance for about half of the population and gross domestic product in China.The TGP design flood volume predicted by the Chinese Hydraulic Design Code (CHDC) recommended annual maximum data sampling based on the Pearson type Ⅲ,or Gumbel models extrapolation method are compared with our proposed"Multivariate Compound Extreme Value Distribution (MCEVD)"theory based P-ISP stochastic simulation method respectively.