The invention provides a simulating experimental device of in situ remediating nitrogen-enriching geothermal water effect. The simulating experimental device comprises a computer, a test bed and an experiment reactor located at one side of the test bed; the computer is arranged on an upper surface of the test bed; the experiment reactor comprises a supporting framework, a heat-insulation bucket and a leak bucket; the shape of the supporting framework is cylindrical; an annular connecting flange is arranged at an outer edge of the top of the supporting framework; the heat-insulation bucket is arranged in the supporting framework; the heat-insulation bucket comprises an outer bucket body and an inner bucket body, which are through from top to bottom; the central line of the outer bucket body is arranged along the vertical direction; the radius of the inner bucket body is smaller than that of the outer bucket body; the inner bucket body is coaxially arranged in the outer bucket body; an annular connecting plate is fixed between the bottom of the outer bucket body and the bottom of the inner bucket body. The simulating experimental device has an excellent simulating effect and can be used for accurately simulating a real condition of remediating the nitrogen-enriching geothermal water in situ by denitrifying bacteria.