Ceramic membranes with the advantages of excellent thermal, chemical and higher permeable properties have attracted more attention and have been applied in turbidity removal, sanitary wastewater and other important industries. However, the ceramic membrane required “coating-drying-sintering” process, in which the process inevitably leads to cracks and wide pore size distribution. In this study, ceramic ultrafiltration membranes with narrow pore size distribution and high permeability were prepared by the dip?coating method using ultrafine spherical alumina powders with high density and smooth surface synthesized by thermal plasma. The microstructure evolution of prepared membranes could be controlled by adjusting the sintering temperature, and the ceramic membranes with a narrow pore size distribution of 25?65 nm and a high pure water permeability of 986.4 L/(m2?h) were sintered at 1250℃. The sintering mechanism of the ceramic membrane was fully investigated and it was found that the narrow pore size distribution of membranes came from the spherical Al2O3 powders with the narrow particle size distribution and high density synthesized by thermal plasma, and the homogeneous sintering necks formed at 1250℃. The result indicated that the pure water flux of the membranes decreased as the sintering temperature increased. It can be explained that the surface of ceramic membranes became denser with the increase of the sintering temperature, resulting in the decrease in porosity and the average pore size. In addition, the prepared membranes were employed to filter the nano-silicon dispersion slurry to evaluate the performance of the membranes sintered under different temperatures. The result indicated that the membrane sintered at 1250℃ showed a higher removal rate of turbidity (99.96%), and the turbidity of the permeate was 0.231 NTU. Finally, the reduction of the permeate flux of the nano-silicon dispersion slurry were analyzed using pore blocking models, and it was found that the cake filtration model was suitable to the prepared membranes.