Abstract: A test apparatus for simulating a seismic dynamic response of an underground cavern includes a loading frame, an overlying model and an underlying model of the underground cavern, a static loading device, a dynamic loading device and a measuring device. A vertical load and a horizontal load are separately applied by the static loading device to the overlying model to simulate real vertical and horizontal in-situ stresses of the in-situ underground cavern. A seismic dynamic load is applied by the dynamic loading device to the underlying model, and then acts on the overlying model to simulate a real seismic ground motion on the in-situ underground cavern. In this way, the present invention satisfies simulation requirements for the seismic dynamic response of the underground cavern to implement a high-fidelity simulation on the underground cavern through unified loading of the in-situ stress static load and the seismic dynamic load.