Since the production started in late 2014, there have been 11 relief wells that have been blocked, which seriously affected the normal production of gas wells. On the basis of analyzing blocked well, according to wellhead pressure, wellhead temperature variation characteristics and hydrate formation depth prediction of different plugging, rapid diagnostic methods for hydrate plugging and composite plugging have been established. Through verification, the diagnosis accordance rate is 100%. At the same time, the comprehensive evaluation method of fuzzy diagnosis is used to evaluate the influence factors, and the source of blockage is analyzed.