The invention discloses a filling simulator for a salt rock cavern, which consists of a stirring device, a pumping device, a simulating salt rock cavern and an image collecting device, wherein the stirring device, the pumping device and the simulating salt rock cavern are connected by a mortar conveying hose and a mortar feeding hose; a camera of the image collecting device is arranged in the front of the simulating salt rock cavern and is controlled by a computer; and a master opening and auxiliary openings which are formed on a cavern cover are matched with a casing pipe, a central pipe, auxiliary opening hollow plugs, master opening plugs, so that the simulating salt rock cavern can realize the simulation of single caverns, dual caverns and multiple communicated caverns. The filling simulator has a simple structure, is convenient to use, distinct in equipment phenomena and multivariant in function, and can simulate the diffusion and settlement phenomena of filling slurry in cavernswith multiple shapes in brine under different filling processes and measure the horizontal migration distance and angles of repose of the caverns.