The alternating test chamber means that the temperature, humidity and time required to be done can be set within the instrument parameters at one time, and the test chamber will follow the set procedure. The damp heat test chamber is to add a damp heat system on the basis of temperature, so that the humidity test can be done at the same time as the temperature test, so that the test effect is closer to the natural climate, and more severe natural climate can be simulated, thus making the tested samples more reliable.