Textile ink jet printing as a new dyeing method with higher resolution, lower pollution, and shorter run length has attracted more and more people's attention. Pigment inks have become one of the main colorant materials in this technology for their excellent light fastness and their suitability to all sorts of textiles. However, most organic pigments of low polarity are hard to wet and disperse in aqueous media, therefore the organic pigments must be modified before their application. In this research, waterborne nanoscale pigment dispersion including Copper Phthalocyanine blue (P.B.15:3), Quinacridone Red pigment (P.R.122), and Monoazo Yellow pigment (P.Y.14) have been prepared by the phase separation method and by the method of direct milling with dispersants, respectively. The properties (stability, particle size, and apparent viscosity) of dispersions prepared by the different methods were compared. The results show that the pigment dispersion has higher stability to alcohols, temperature, and storage, and also lower viscosity; the phase separation method was more suitable to preparation of pigment dispersion for formulations of ink jet inks than the method of direct milling with dispersants; TEM images indicated that the pigment particles were uniformly distributed in aqueous media, and the x-ray diffraction spectra indicated that the pigment crystal structure was unchanged after encapsulation in the phase separation method.