Spacecraft gas replacement method and gas experiment device

The invention relates to the technical field of gas experiment devices, in particular to a spacecraft gas replacement method and a gas experiment device. The method comprises the following steps: S1, filling a gas experiment cavity of a gas experiment device to be subjected to gas replacement with preset gas until a first preset pressure difference is reached, and exhausting the preset gas filled in the gas experiment cavity until a second preset pressure difference is reached; and S2, the step S1 is executed repeatedly till the preset condition is met, and gas replacement is completed. The first preset pressure difference and the second preset pressure difference are set, the gas experiment cavity is subjected to gas replacement for multiple times, the overpressure condition can be avoided, the gas experiment cavity is prevented from being damaged, after gas replacement is completed, the gas experiment cavity is filled with preset gas such as nitrogen, the preset gas in the gas experiment cavity can meet the