Abstarct: In this study interfacial polymerization technique was employed by applying trimesoylcholoride(TMC) and piperazine (PIP) as reagents to prepare polyamide(PA) skin laxyer on a polyethersulfone(PES) support. The surface of obtained thin laxyers modified with poly (amidoamine) (PAMAM-COOH) dendrimers. The different concentrations of PAMAM [0.3, 0.6, 1 wt%] were chosen to modification process. The different concentrations of dendrimers in aqueos phase and their effects on morphology and performance of nanofiltration membrane were investigated. The polyethersulfone support was prepared by dissolving PES in dimethylformamid (DMF) with PEG and acrylic acid. Thin film composite membrane was prepared via polymerization between aqueous PIP and organic TMC solution. The performance of prepared membranes was analyzed using a dead-end system. The rejection of resulting membranes increased with decrease concentration of PAMAM for Na2SO4 concentration. The salts rejections sequence of resulting membrane is NaCl<Na2SO4, which refers to the negative charged NF membrane. The resulted membranes are suitable for separating cationic solutes from others. These results demonstrate that the rejection of salts is not only related with the pore size of the membrane, but also largely depends on the electrostatic action between the membrane and ions in solution. The rejection of Na2SO4 for NF was 92%. FTIR-ATR ,AFM, SEM,Zeta potential and water contact angle were employed to characterize the chemical and physical changes in resulting membranes.