In order to efficiently use low rank coals, thermal dissolution (TD) of Shengli lignite (SL) was carried out in a mixed solvent toluene/ethanol with synergistic effect and the TDSL was analyzed with gas chromatography/mass spectrometry (GC/MS). Seventy one oxygen-containing organic compounds (OCOCs) including alcohols, phenols, ethers, ketones, acids, and esters were detected. Among the OCOCs, the relative content of phenols and esters is higher, and their possible formation mechanisms are discussed. Hence, understanding the structure of OCOCs in lignite at the molecular level is more promising to convert the low calorific fuel into high-valued organic compounds.