Abstract: In order to investigate the impact of inherent minerals on pyrolysis for lignite with high ash content,some py- rolysis experiments were conducted in Drop Tube Reactor and Thermogravimetric analyzer at 800 -1 200 ℃ . Lignite samples containing different ash and mineral compositions were prepared by separation,acid demineralization and min- eral addition. Results show that the inherent minerals could reduce the pyrolysis reactivity of lignite and increase the char yield at low temperature (800 ℃ );AAEM played a major role. While at high temperature (≥1 000 ℃ ),the in- herent minerals reduced the char yield by in-situ catalyzed steam-gasification. The reduction in char yield was directly related to the ash and internal water content of coal samples,as well as the total amount of basic metals. Raman analy- sis showed the inherent minerals can disorder the microcrystalline structure of char and inhibit the fracture of cross- linking bonds. The surface of char was increased by Ca as the main role of inherent mineral composition. With the py- rolysis temperature increasing,the excessive mineral will inhibit the further expansion of porosity for chars.