UV Flexo Ink is composed of pigment particles, pre-polymer, monomers, photo-initiators and various additives. The pigment dispersion has important influence on the property of UV Flexo Ink. In order to discuss the effect, UV Flexo Ink formulations were designed. Through changing the dispersing conditions, the ink samples which have different dispersion states were obtained. The particle size distribution, viscosity, curing speed, the solid density of proofs, and print contrast were tested, and the effects of dispersion were also analyzed. The experiment results show that pigment dispersion has a variety of influences on ink printabilities.