Abstract: The present invention provides a method of water flow erosion for marine gas hydrate exploitation. Based on the characteristics of higher permeability around gas hydrate exploitation well, controlling the seawater flow process by the pressure difference between hydrate reservoir and gas hydrate exploitation well. And the chemical potential difference between hydrate phase and water phase is the main driving factor for promoting the hydrate decomposition. Meanwhile, the salinity will increase and then the phase equilibrium temperature of hydrate will increase during seawater flow process. The water flow erosion accelerates the heat and mass transfer in hydrate reservoir to promote the efficient and complete decomposition and collection of hydrate. And the method of water flow erosion can decrease the risk of the geographical destruction caused by the large pressure drop. The present invention also provides the combination modes of water flow erosion with depressurization, thermal injection and other methods.