The invention relates to a device and method for measuring the concentration distribution of a CO2 soluble surface active agent in a CO2/water system in the three-dimensional seepage process. The device comprises a three-dimensional rock core model; an inlet end of the three-dimensional rock core model is connected an emulsion generator and a crude oil injection device which are connected with each other in parallel; an inlet end of the emulsion generator is connected with a CO2 gas injection device and a surface active agent injection device which are connected with each other in parallel; an outlet end of the three-dimensional rock core model is connected with a gas source bottle and a liquid-containing bottle which are connected with each other in parallel by a back-pressure valve; sampling holes are respectively formed in the top surface and one side surface of the three-dimensional rock core model at equal intervals; the sampling holes are communicated with a rock core arranged in the three-dimensional rock core model; each sampling hole is connected with a sampler by a pipeline provided with a valve. The different parts of the model are sampled, a water phase is separated from a CO2 phase, a CO2 phase sample is dissolved in water, and the concentration of the surface active agent is detected by a high performance liquid chromatography (HPLC). The device and the method are simple in operation and high in measurement accuracy rate.