Abstract: A system for deep sediment flow culture simulating in-situ water pressure includes 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, 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, and an outlet of the porous medium pipe is connected with one end of the depressurized water outlet pipe, the other end of the depressurized water outlet pipe extending into the water catcher.