The invention provides a device and a method for testing a
moisture expansion coefficient of a
composite material under a
moisture supplementing condition. The testing device comprises a vacuum tank,and a
quartz test piece, a
humidity sensor, a temperature sensor, an air
pressure sensor, a displacement sensor and a load sensor which are arranged in the vacuum tank, wherein the vacuum tank comprises a first
test chamber, an environment chamber and a second
test chamber which are sequentially connected from top to bottom; the
quartz test piece is fixedly connected with the first
test chamber, and overhangs and penetrates through the environment chamber and the second test chamber; the first test chamber, the environment chamber and the second test chamber are communicated by means of the
quartz test piece, and the quartz test piece is detachably connected with a sample in the environment chamber; and the load sensor is used for testing the
mass change of the sample, and the displacementsensor is used for testing the
length change of the sample. According to the testing device and the testing method provided by the invention, dynamic measurement of the
mass and length changes in themoisture supplementing process under any constant
humidity condition from 0% to 95% can be realized.