Abstract: In order to investigate different hydrothermal treatment conditions affected to the pore structure and surface property of Shengli lignite, the test was cond ucted on the total pore volume, average pore radius and specific surface area of the coal samples after hydrothermal treatment.The balanced moisture content and the Zeta potential were applied to describe the surface property of the coal sample.The results showed that the total pore volume, average pore radius and specific surface area of the coal samples after hydrothermal treatment were higher the raw coal.After the treatment under the conditions of the temperature 320。C，the constant temper ature time 15 min, the N2 initial pressure of 2 MPa and the coal and water ratio of 5 : 1, the specific surface area of the sample would the max in variation and would be increased by 96.72% than raw coal.The temperature rising, the constant temperature time enlarged and the initial pressure increased all could obviously reduce the wat er absorption of the coal sample and the max reduction of the balanced moisture content of the coal sample was 76.61%. The Zeta potential absolute value of Shengli li gnite would be reduced obviously after hydrothermal treatment and was related to the removal of the carboxyI and hydroxyI in the coal during the hydrothermal treatmen t process.