Abstract: It discloses a system for deep sediment flow culture simulating in-situ water pressure, comprising a flow culture apparatus, an inflow pressurizer and an outflow depressurizer, wherein the inflow pressurizer comprises a pressure tank, an air inlet pipe, a pressure regulating valve, a pressure-resistant container and a first support, wherein the pressure tank is connected with an air inlet of the pressure-resistant container through the air inlet pipe, the pressure regulating valve is arranged on the air inlet pipe, and the pressure-resistant container containing in-situ overlying water added with isotopes is placed on the first support, a water outlet of the pressure-resistant container being connected with a water inlet pipe of the flow culture apparatus; the outflow depressurizer comprises a porous medium pipe, a second support, a depressurized water outlet pipe and a water catcher.