Abstract: Abstract: The ashing characteristics of Baori lignite were studied by plasma low temperature ashing method (LTA) and medium temperature ashing (MTA). The results showed that the content of the residue was 18.59% through LTA treatment, and the XRD mineralization peak was clear; The oxidation method was showed a difference with the temperature of LTA. The organic matter is not completely oxidized and ashing residue are 32.58% and 21.67% respectively at 150~200℃. The ashing is more complete at 250℃ and the residue is 17.51%, and the characteristic peak of mineral is easily to identified.The ashing product is over-oxidized and mainly composed of oxidized minerals after higher than 300℃. Method of MTA at 250℃ can be used instead of LTA method, and the required ashing time is 20h.