Abstract: Panhandle-Hugoton gas field in North America and Puguang gas field in Sichuan basin of China are all giant marine carbonate gas fields in the world. It is suggested from comparison and analysis of the geological setting, pool?forming condition and process of these two gas fields that Panhandle-Hugoton and Puguang gas fields are all characterized by multiple source rocks, good reservoir rocks with middle?high porosity and permeability, and the gas pools suffered multistage reformation and stabilization controlled by late tectonization, and gypsum and salt cap rocks. The most difference between them is the development degree of their cap rocks. The thickness and continuity of regional gypsum and salt cap rock in Panhandle-Hugoton gas field are clearly superior to those in Puguang gas field, showing that the sealing and preserving condition are the key factors for the formation of giant gas field under the geologic conditions of sufficient gas source and good reservoir. It is predicted that other giant gas fields the same as or even larger than Puguang could be found in the areas where both reef?flat reservoirs in Feixianguan formation and gypsum and salt cap rocks in Jialingjiang formation are developed, such as Wanzhou and Dazhu areas, in South China