The invention provides a hypotonic hydrate sediment permeability measurement method and device based on impulse attenuation analysis. The device comprises a reaction container, wherein an intermediatecontainer is arranged at the downstream end of the reaction container, ISCO (International Standard Classification of Occupations)plunger pumps are connected with the two sides of the reaction container, the two pumps are both connected with a gas supply bottle, and pressure of the upstream end can be respectively measured and pressure difference between the two ends of the reaction container can be mesured by a data collection system and a temperature in the reaction container can be measured. By means of the device, permeability of a porous medium with higher fine granularity and higher hydrate saturability can be measured, and the problem that a traditional measurement method has difficulty in forming steady seepage in the medium is resolved. The method is different from a traditionalpermeability measurement method, an unsteady state method can be relied on the method to measure the permeability of the porous medium without needing to form steady seepage and measure flow data, and absolute permeability can be directly calculated out according to the change situation of the pressure difference at the two ends of the reaction container.