A number of geological workers take it seriously that palaeokarst reservoir in the Huanglong Formation of Carboniferous are the most important types of natural gas reservoir.Through the sign recognition and the causes analysis of karstification, palaeokarst landform in the Huanglong Formation of Carboniferous is resumed with the erosion thicknesses method, geomorphologic method and impression method in eastern of the Sichuan Basin. The karst morphological unit, such as karst highlands, karst slopes and karst basin and the minor morphological unit, such as peak cluster, ponor, hillsides, valley, shallow depression, remnant hills and trough valley are subdivided. The seven subareas of palaeokarst landform are subdivided in the area of the east Sichuan Basin, and the karst morphological characteristics is studied in different subarea. It is considered that the geographical location of palaeokarst landform and the characteristics of karst morphological unit have significant differences and a direct impact on the formations of gas fields.On this basis, the palaeokarst reservoirs development controlling factors in eastern Sichuan Basin are analysed and it is put forward that structure, climate, lithology, strata, ancient terrain, hydrogeologic conditions and different karst morphological forms influenced or even controlled the development and regional distribution of palaeokarst reservoirs.So the research findings will provide reliable evidence for the palaeokarst reservoirs evaluation and favorable area optimization.