Pyrolysis is an important means of lignite modification and upgrading. In order to study the changes of phase and microstructure of lignite char prepared at different pyrolysis temperatures, lignite samples from Puhe coal mine in Shenbei mining area, were pyrolyzed at three pyrolysis characteristic temperatures (400 ℃,700 ℃ ,1000 ℃) to prepare lignite char samples. The physicochemical structure of lignite coke samples was analyzed by SEM, XRD, Raman, FT-IR, XPS, N2 adsorption experiments. The results show that with the increase of pyrolysis temperature, the aromaticity of coke sample is enhanced, the oxygen-containing functional groups O-H, C=O and C-O of coke sample are greatly reduced, surface carbonaceous functional groups, the intensity of C-C increased and the intensity of C-H reduced. At 400 ℃ and 700 ℃, the microcrystalline structure defects of coke samples increased, while at 1000 ℃, the microcrystalline structure of coke sample tends to order and changes to graphitization. The specific surface area and pore volume of coke samples first increased and then decreased with the increase of pyrolysis temperature. 700 ℃ coke sample has the largest specific surface area (117.0637 m2/g) and pore volume (0.068134 cm3/g). Increasing pyrolysis temperature is conducive to the development of microporous structure of coke sample.