Abstract: The emergency classification of the nuclear power plants with wet storage spent fuel is analyzed, based on the threats of the criticality return of spent fuels and the losing of shield, heat removal and containment. The parameters for classification can not only be monitored, but also can be used to character the safety level of the spent fuels. The representative values of water level, temperature and dose rate and the emergency classification of the spent fuel for Fangjiashan Nuclear Power Plant are provided.