The invention provides an aerostat envelope material as well as a joint natural aging test device and method thereof. The joint natural aging test device comprises a test rack, at least one aerostat envelope material test piece and a meteorological station, wherein the aerostat envelope material test pieces have internal preset capacities and are suspended inside the test rack; a charge/discharge valve and a pressure difference sensor are mounted on the surface of each aerostat envelope material test piece; a temperature-humidity sensor is mounted inside each aerostat envelope material test piece; the charge/discharge valves, the pressure difference sensors and the temperature-humidity sensors are all connected with the meteorological station; the meteorological station comprises an industrial personal computer; the industrial personal computer is used for keeping pressure inside the aerostat envelope material test pieces within a set range through the charge/discharge valves and the pressure difference sensors. By adoption of the joint natural aging test device, the pressure load to aerostat envelope materials can be simulated, different radiation angles can also be simulated, and moreover natural aging situations of the aerostat envelope material and the joint of the aerostat envelope material in practical use can be accurately simulated.