The invention discloses a measuring method of gas hydrate specific surface area and adsorbance. A high-pressure physical adsorption instrument, a gas chromatograph and an X-ray diffractometer are adopted to accurately measure adsorbance of gas hydrate adsorbing gas and weight of a to-be-measured gas hydrate sample, and further the specific surface area of the gas hydrate is calculated finally. Themeasuring result has high reliability and high uniformity. The measuring method solves the technical problems in the prior art that during the gas hydrate adsorbing measuring process, the gas hydrateis liable to decompose and to release gas, measuring of gas adsorbance and the weight of the to-be-measured gas hydrate sample is disturbed, measuring difficulty is high, and the lack of an effectivemeasuring method to achieve effective and accurate measuring of the natural gas hydrate specific surface area and adsorbance. The measuring method is of great significance to study the kinetic mechanism of natural gas hydrate decomposition, establishment of a natural gas hydrate production model and other aspects.