Abstract: in order to studly the microstoucture of lignie afected to it combustion characteristcs the Thermal cravimetric Analzer and Fourier Transform lnfraredSpecrometer(FTiR) were used to analize theperormanceso tructure and combustion of seven typicalinte samples.Th disiribution and thestructure of funcionagroups in lignte were obtained though fting the ifrared specraline by Gaussian peaks.The resuits show that aromatic structure is stable and activity is low.which isunfavorable forlignte's fre.The content f aliphatic hydrocarons affect the burnout temperature and have a negative efect on coal burning out.The Oxygen containing functonal groups and hydroy groups can improve the combustion speed and reduce the activation energy oflignite respectively which can pronote lignite's combustion.