Abstract: A capsule-type expansion body based on geothermal heating, and a method thereof for plugging formation leakage and improving formation bearing capacity are provided. The capsule-type expansion body includes a capsule shell, and a liquid or solid temperature-controlled expansion material, which circulates with a drilling fluid and enters formation fractures and pores around a well and at a long distance. After heating to a certain temperature range with formation temperature, it expands rapidly and greatly to adaptively plug various types of leakage formations with elastic deformation and improve the formation bearing capacity. The capsule-type expansion body is divided into physical gasification type or chemical decomposition reaction type according to expansion principles of the liquid or solid temperature-controlled expansion materials. It maintains an unexpanded state during ground transportation and circulation in a wellbore at a relatively low-temperature.