The invention provides an experiment simulation device and method for quantitatively researching karst collapse. The device comprises a model main body, a water supply unit, a constant-pressure sand-soil collecting unit, a seepage field monitoring unit and a ground deformation monitoring unit, wherein the model main body is karst covering layer and karst bed rock simulation equipment and comprises a covering layer cavity and a karst ground layer cavity, wherein the karst ground layer cavity is located at the lower part of the covering layer cavity and is communicated to the covering layer cavity; the power supply unit comprises a covering layer water supply unit communicated with the covering layer cavity and a karst ground layer water supply unit communicated with the karst ground layer cavity; and the constant-pressure sand-soil collecting unit is used for collecting karst collapse sand-soil quantity in different moments when a karst water level is constant in the whole karst collapse process and quantitatively evaluating a collapse evolution process. According to the experiment simulation device, the karst collapse process is quantitatively researched by monitoring the dynamic change of the seepage field of the covering layer and the leakage quantity of collapse sand of the covering layer.