During the latter part of steam injection for extra-heavy oil reservoirs, the issues of high water cut, low oil-steam ratio, and poor production efficiency often exist. So it is urgent to transform the development mode. As an important thermal recovery replacement technology, in-situ combustion has the advantages of wide adaptability and high recovery rate. It is important to explore the adaptability of in-situ combustion for high efficiency development. Taking Block X as an example, the experimental research was carried out from two aspects of heat release and combustion stability. Combined with the characteristics analysis of viscosity-temperature and total hydrocarbon chromatography, the feasibility of in-situ combustion was studied through static oxidation experiment of synchronous thermal analysis and dynamic in-situ combustion experiment of one-dimensional combustion tube. The results show that when the temperature reaches 435 ℃ for block X, the oil is burned and a lot of heat is released, which can maintain the continuous advance of combustion front. As a result of the crude oil's high viscosity, there is oil accumulation in the process of in-situ combustion, and the formed oil wall obstructs the passage of crude oil, resulting in slow propulsion of fire line and unstable combustion. The exploration presents effective theoretical insights to transform the development methods for similar reservoirs.