Natural diatomite contains a large amount of amorphous silica, which as siliceous material can be used for silicate products.The specimens of humidity controlling material based on diatomite were made by some critical process measures, such as pouring slurry into mould, pressure dewatering and atmospheric steam curing.The effects of the ratios of raw materials and the pressure of dewatering on bending strength, the performances of moisture absorption and desorption were studied, the microtopography of specimens were analyzed by scanning electron microscope.The results of single factor experiments showed that the specimen had the maximum bending strength with 2:6 of CaO/SiO2 mole ratio, the bending strength of the specimen showed a rising trend with the increase of the cement content and the dewatering pressure;A slight increase in bending strength could be found while rising desulfurization gypsum content;For the absorption and desorption performances, the CaO/SiO2 mole ratio were significantly influence, and the effect of the content of cement and desulfurization gypsum content,dewatering pressure could be ignored.The SEM photos showed that diatomite hydration products in internal holes increased with CaO/SiO2 mole ratio, which was related to the performances of moisture absorption and desorption.