A co-current operation for SO2 absorption by water was performed in a laboratory-scale packed column. The effects of L/V (liquid-gas ratio) and F (gas phase loading factor) on the SO2 absorptivity were both investigated. The absorptivity for co-current increased with the increase of L/V and the percentage of absorptivity increase at higher L/V is larger. At lower F, in regular packing there is fluctuation of absorptivity with F increased, but in random packing there is not. With the increase of F, the absorption curve slowed down. It is proposed that in order to obtain a steady desulfurization efficiency, F factor in both kinds of packings should be higher than 4 kg0.5/m0.5s. For absorptivity, which could be reached by both co-current and counter-current, it is suggested that co-current is better because of the higher gas velocity.