A novel organic-inorganic nanocomposite NF membrane containing SiO2 were prepared by interfacial polymerization on polysulfone (PSF) ultraﬁltration membrane with poly(amidoamine) (PAMAM) dendrimer and trimesoyl chloride (TMC) as monomers. The membranes were investigated by Thermal Gravimetric Analysis (TGA), Field Emission Scanning Electron Microcopy(FESEM) and Energy Dispersive X-ray Detector(EDX), then the separation performance of salt solution was investigated. The results indicated that the nanoparticles were well-distributed in the membranes. The addition of SiO2 in the skin layer increased thermal stability and improved roughness and hydrophility of membrane. The pure flux for PA-SiO2 increased than neat PA membrane while the rejection rate of Na2SO4 salt solution was lower than the latter.