In order to effectively and widely use low-rank coal and biomassBiomass, the co-extracted product was extracted from GL(Guole) coal and biomassBiomass by polar solvent N-2-methyl-2-purrolidinone (NMP) at high temperature and high pressure. The structures of the co-extracted product and residues were characterized by element analysis and XPS analysis. The effects of temperatures, solid–liquid ratio, and extraction time on the extraction yieldsExtraction yield of co-extracted products were studied. Moreover, the extraction mechanism of the co-extracted product at mild conditions is proposed. The results show that the ash contents of the co-extracted products from GL coal and biomassBiomass are significantly lower than GL coal, and the volatile contents and H/C are significantly improved. For GL coal, with the increase of biomassBiomass/coal ratio, the extraction yieldExtraction yield of GL is improved evidently from 56.25% to 71.44% and the ash content is decreased from 0.68% to 0.59% at suitable conditions.