The invention relates to a different-orbit-altitude background radiation dynamic simulation method and device, a computer storage medium and a background radiation simulator. The method includes the steps that according to the orbit altitude of a to-be-simulated spacecraft and the distance between a spacecraft model and the radiating surface of the background radiation simulator in a simulation system, the effective radiation radius of the radiating surface of the background radiation simulator is calculated; the background radiation simulator comprises multiple arc-shaped radiation blocks, circular areas with different radii are formed by the radiation blocks firstly, all the circular areas with the different radii are concentrically arranged to form the whole radiating surface of the background radiation simulator; and according to the calculated effective radiation radius, the temperatures of the radiation blocks with the radii not larger than the effective radiation radius in the background radiation simulator are controlled to be increased to a first target range value, and the temperatures of the radiation blocks with the radii larger than the effective radiation radius in the background radiation simulator are controlled to be reduced to a second target range value. Through control over temperature increase or reduction of the radiation blocks in the different radius positions of the background radiation simulator, radiation heat flows at different orbit altitudes can be simulated.