The invention discloses a closed box experimental device for glass breaking and falling with the effect of thermal load, comprising a modular box body, a radiative heating system, a smoke extraction system, a water curtain spray system, a control system and a measurement system. A multi-regulation radiation source is adopted, so that the distance between the radiation source and the glass, the heating rate of the radiation source, the glass type, the size, the thickness and the edge flatness of the plane, the material of a glass fixing frame, the edge covering width of the glass, an immovableglass edge filler, the indoor pressure, the water curtain angle, the flow rate of a water curtain jet, the number of water curtain nozzles and the water curtain jet direction can be regulated; therefore, the influencing factors of the glass breaking with the effect of thermal load can be considered completely. Simultaneously, the heating rate of the radiation source can be effectively controlled,thereby being capable of preventing the defects of other experimental devices, such as overquick temperature rise and difficulty in observing the glass breaking process to a certain extent.