Prepolymer and monomer which are the main components of the UV ink have significant influence on the performance. By changing the proportion of prepolymer and monomer to make the different kinds of UV offset ink samples, the samples’ flow curve, yield stress, curing rate, glossiness, emulsification ratio, solid density and ink transfer rate were tested. And the effects of the proportion of prepolymer and monomer on the performance of UV offset ink were studied. The results show that with the decrease of prepolymer, the viscosity, yield stress and glossiness of the ink were reduce, and the curing rates were more or less the same. The emulsification ratio, solid density and ink transfer rate increased with the decrease of prepolymer.