Abstract: Aiming at the serious re-absorption problems on of dewatered lignite,the paper with the CaCl₂ electrolyte processing the lignite,studied the pore characteristics variation of lignite and its influence on coal quality before and after electrolysis by low temperature nitrogen adsorption.It was shown that with the increase of the electric potential gradient,the open porosity was changed,the pore size distribution was changed widely,the number of large size pore was increased,the specific surface area and the total were reduced significantly,the average pore diameter increased significantly,the re-adsorption moisture was reduced obviously.when especially electric potential gradient being 2.0 V·cm^-1,the special surface area and the total pore volume were respectively reduced to 18.32% and 62.96% of the original lignite,the average pore diameter was increased by 436.86%,the internal moisture after re-adsorption for 1day is only 2.82%.