The phenomenon of excessive water production in the horizontal well is more than that in vertical well. Horizontal well is becoming universalized in the low-permeability oil and gas field development, but there are fewwater shutoff methods and techniques aimed at horizontal wells. By conducting the wetting transition experiment to typical rock sample, the applicable chemical gas wetting transition agent is determined and the thermal stability and formation compatibility are studied. The visual physical model of horizontal well water shutoff is established, the experiments before and after the using of wetting transition agent are compared, and water influx, water influx rate and water cut characteristic curves are obtained. The experimental result shows that gas wetting agent technology of horizontal well water shutoff can be used to delay breakthrough time, improve water free recovery and decline water cut.