Water contaminants, especially bacterial and viral contaminants, have substantially negative impacts on human health because of their wide variety and incredibly small sizes. To develop a nanofiber filter with a high adsorption capacity, a positively charged SiO2/Y2O3 composite membrane with a plum-flower-like structure was prepared by self-assembly and heat treatment. The effects of the hydrothermal temperature and reaction time on the morphology of the composite nanofiber membrane (NFM) were investigated. In the composite NFM, the Y2O3 nanoflowers were tightly bound to the SiO2 nanofiber support. The possible formation mechanism of the composite NFM with a plum-flower-like structure is discussed. The results indicated that the Y2O3 nanoparticles were attached to the SiO2 nanofiber support via a Y-Si-O chemical bond. The surface charge of the composite NFM and its adsorption properties toward water contaminants were characterized. The isoelectric points (IEP) of the composite NFM calcinated under a N-2(96%)/H-2(4%) atmosphere was 9.23. The maximum bacterial retention was close to 100% and the log reduction values (LRV) of the bacteria were 6. Viral contaminants were simulated using a small molecule with two negative charges, titan yellow, with a maximum saturated adsorption capacity and removal rate of the plum-flower-like NFM for titan yellow were 87.96 mg/cm(3) and 99.999%, respectively. After reusing a membrane five times, the composite NFM retained a removal rate of 95.641%. This positively charged SiO2/Y2O3 composite NFM with a plum-flower-like structure has broad application prospects in the fields of contaminant removal and virus filtration.