Abstract: With cavitated creosote oil as a swelling solvent,nature swollen Xigou coal sample was secondly swelled me- chanically by a planetary ball mill for investigating the effect of swelling mechanically on the properties of direct hydro- genation liquefaction of the sample. The investigating results indicate that after the sample is swelled mechanically,the structure became more loose,the volume average diameter and true density decreased by 60. 52% and 8. 06% ,respec- tively,and the specific surface area and swelling degree increase by 90. 91% and 25. 18% ,respectively. The weight loss process might be still divided into three phases,i. e. 110-330,330-550 and 550-1 000 ℃ ,but the weight losses increase by 189. 15% ,28. 22% and 30% ,and the rates of weight loss increase by 208. 9% ,24. 62% and 30. 01% , respectively,and the final weight loss increases by 64. 79% . The fal decreases from 0. 31 to 0. 22 and Xb increases from 0. 12 to 0. 21. Yields of asphalt,oil and conversion increased by 40. 78% ,8. 87% and 8. 44% ,respectively,gas yield decreased by 36. 03% ,and H2 consumption decreased slightly.