Abstract: For applying nano-particles to the funtional finishing of textiles, nanometer MgO was prepared by direct precipitation method with magnesium nitrate and sodium carbonate decahydrate as raw materials, and its structure and property were characterized by DSC and XRD. The effects of concentration and ratio of reactants, reaction temperature, calcining temperature and calcining time on the activity of MgO nanoparticles were analyzed, and the optimal reaction conditions for preparing nanosize MgO were determined as follows: reaction temperature 40℃, time of the ultrasonic vibration 50min, concentration of the reactant 1.5mol/L, ratio of the reactants 1:3, calcining temperature 550℃ and calcining time 2.5h. The antistatic properties of cotton and polyester fabrics finished with nanometer MgO as an antistatic finishing agent were tested. The results show that the treated fabrics have been imparted with good antistatic properties.