Abstract: In order to enhance the utization fficiency of lignit in China.taking the lintes samples from Hunbeist Yuanbaoshan Wulanchabu Xnganmeng and Baoqing Area as research subjects and chosing the change rate of paricle size as the measure idex of thermal cracking.the paer investigated the fFfects of ceal ank.nitial average paricle sze,heating temperature and moistre content on lignie thermal cracking.the stoucture characterisics of the debris afer themal cracking were aso studied.T'he results showed that lignite's therm al racking propery were cifferent with dfferent califcaion dege. The lager the nital average paticle s ze was and the higher the heating temperature w/as the stonger the thermal crackingoflignite waould be.The moisture contern of linte woas the majr factor afirced it thrmacracking aftr drying 1 hour at 150 0℃,the themal cracking of the samplecould be decreased by more than half compared with av coal. The linite produced a lot of new holes in th thermal cracking process the higher the moisture content and voatle content of lignie were,the more developed the porestructure of the debris aier thermal cracking would be.