To reasonably utilize the coal direct liquefaction residue (DLR), contrasting research on the co-pyrolysis between different low-rank coals and DIR was investigated using a TGA coupled with an FT-IR spectrophotometer and a fixed-bed reactor. GC-MS, FTIR, and XRD were used to explore the reaction mechanisms of the various co-pyrolysis processes. Based on the TGA results, it was confirmed that the tetrahydrofuran insoluble fraction of DIR helped to catalyze the conversion reaction of lignite. Also, the addition of DIR improved the yield of tar in the fixed-bed, with altering the composition of the tar. Moreover, a kinetic analysis during the co-pyrolysis was conducted using a distributed activation energy model. The co-pyrolysis reactions showed an approximate double-Gaussian distribution. (C) 2019 The Chemical Industry and Engineering Society of China. and Chemical Industry Press Co., Ltd. All rights reserved.