A novel evaluation method is investigated for UV curing process in printing system. The method is based on the measurement of conducivity change by the photopolymerization of UV curable inks and paints. It is found that the decrease of conductivity is caused by photopolymerization of epoxy monomer during UV curing process of ink film and the by the rate of UV curing. It is possible to make the dynamical evaluation the curing rate of UV curable ink in curing process by this method.