The invention relates to the technical field of test devices, in particular to a constant-temperature and constant-
humidity test box. The constant-temperature and constant-
humidity test box comprises a 
barrel-shaped 
test chamber arranged in a vertical direction, a base, a heating device, a refrigerating device, a humidifying device and a balance weight 
piston, and the base is provided with a support used for installing a sample; a test space is formed in the test cabin and is positioned between the counterweight 
piston and the base; the humidifying device is used for adding wet air into the test space, the humidifying device comprises an atomizing device and a compressor, the atomizing device atomizes water in the water tank to generate 
water vapor, and the compressor presses the 
water vapor into the test space; and the test box further comprises a circulating fan, a 
honeycomb rotating wheel, a temperature sensor, a 
humidity sensor and a controller. According to the constant-temperature and constant-humidity test box, after 
water vapor is condensed and liquefied, due to the fact that the balance weight 
piston can freely slide under the action of gravity, the air pressure in the 
test chamber is kept constant, and the air pressure in the 
test chamber can be kept stable without an air 
pressure sensor.