The utility model provides a moisture tester. The moisture tester comprises a base and a heating cover, a heating cavity is formed in the heating cover, and an electric heating wire and a temperaturesensor are mounted in the heating cavity; a cover body of the heating cover comprises a stainless steel outer shell, a heat preservation layer and an aluminum alloy inner shell which are arranged fromoutside to inside. A cold air inlet hole and a hot air outlet hole are formed in the side wall of the heating cover and penetrate through the stainless steel outer shell and the heat preservation layer, a plurality of cold air dispersing holes and hot air collecting holes are distributed in the side wall of the aluminum alloy inner shell, the cold air dispersing holes communicate with the cold air inlet hole, and the hot air collecting holes communicate with the hot air outlet hole; a weighing cavity is formed in the base, the weighing cavity is communicated with the heating cavity, an electronic balance is installed in the weighing cavity, a crucible base is fixed to the electronic balance, and the crucible is arranged on the crucible base; an electronic display screen is further installed on a front panel of the base and electrically connected with the electronic balance and the temperature sensor. The cooling device can dissipate heat automatically and quickly, and is high in cooling efficiency, free of thermal shock and high in use comfort.