Fusion characteristics of ash residues from Xiaolongtan lignite pressurized fluidized-bed gasification were investigated with ash fusion point detector and sintering temperature analyzer. The results show that the sintering temperature (Ts) and ash fusion temperature (AFT) of three ashes residues decrease from gangue ashes to agglomerate to slag, which result from the differences of mineral type and content in three ash residues, and the decrease of the total basic constituents increases the AFT. The formations of three ash residues during gasification are the interactions among mineral matter and their transformations under high temperature.