Thin film composite (TFC) membranes formed by polysulfone fibers (PSFs) substrates and polyamide (PA) active layers were investigated and their water flux and salt rejection were assessed through forward osmosis (FO) process. The PSFs substrates were fabricated by single/dual-nozzle electrospinning method with average diameter of 0.49 to 0.59 µm. Functionalized carbon nanotubes (fCNTs) were also prepared and equipped with Fe3O4 particles. The formation of Fe3O4/fCNT hybrid was confirmed by SEM and XRD analyzes. The PA active layer was coated on the PSFs substrate via interfacial polymerization between m-phenylenediamine and trimesoyl chloride. The 0, 50, 100, 200, and 500 ppm of Fe3O4/fCNT hybrid were embedded in PA active layer during the IP process, and the obtained membranes were characterized by FTIR, EDS, XRD, SEM, AFM, and BET analyses. The water contact angle results showed that the hydrophilicity of TFC membranes was increased by increasing the concentration of Fe3O4/fCNT in the PA active layer. The experimental results also revealed that the water flux and salt rejection could be affected by the Fe3O4/ fCNT concentration within the PA active layer and the type of PSFs substrate. When compared to the single-nozzle, the FO results confirmed that higher water flux and salt rejection could be achieved by dual-nozzle electrospun PSFs membranes. By using 200 ppm of Fe3O4/fCNT in the active layer, the maximum water flux of 25.0 and 27.4 L·m-2·hr-1 was achieved by the single and dual-nozzle electrospun TFC membranes, respectively. In addition, the FO results indicated that, with the maximum rejections of 90% and 94% for Na2SO4 and NaCl, the higher the Fe3O4/fCNT concentration in the PA active layer, the higher the salt rejection of the membrane.