A three-dimensional dynamic load loading large-sized similar material simulation platform includes a flexible force transmission rubber, a box body and a simulation platform; a displacement sensor is arranged between a guide rail and a top cover plate, and a front cover plate, side covers, a rear cover, the top cover plate, hydraulic cylinders, the guide rail, the displacement sensor and a pressure sensor form a cover plate loading device; and the flexible force transmission rubber is arranged at the inner side of the front cover plate, the side cover plates, the rear cover plate and the top cover plate. The three-dimensional dynamic load loading large-sized similar material simulation platform is provided with the flexible force transmission rubber, the flexible force transmission rubber has the characteristics of flexibility, changeability, and incompressible size, a water injection tube is arranged on the side surface of the box body, and is used for introducing a filling material to the goaf and flooding water to a simulated rock stratum after the coal seam is exploited, and high pressure gas is added to a simulated coal seam to stimulate gas in order to meet different experiment requirements.