In order to overcome the shortage of adsorption ability loss after sepiolite is HCHO-saturated, static adsorption experiments were applied to evaluate the effects of heating temperature on absorbing traces of gaseous HCHO for sepiolite, and scanning electronic microscopy, X-ray diffraction, infrared absorption spectroscopy, thermogravimetry and BET specific surface area analysis were adopted to investigate the related mechanisms. It was resulted that silica-gel desiccant elevated the sepiolite’s adsorption ability of traces of gaseous HCHO and reduced the final HCHO concentration lower than the legal safety upper limit. The sepiolite heated at temperature ≦400 ℃ held favorable HCHO absorption properties, while those heated at temperature ≧500 ℃ showed significantly reduced HCHO absorption properties. Under comprehensive characteristics, it is proposed that the crystalliferous water in sepiolite could chemically absorb HCHO and the structural microholes, basically composed of zeolite holes, could be occupied by HCHO through physical absorption. After heated at temperature ≧450 ℃, sepiolite lose the crystalliferous water irreversibly and the zeolite holes collapse that lead to the adsorption ability drastically reducing. The research supports sepiolite to regenerate adsorption ability by heating at temperature below 450 ℃ at which the escaped HCHO could be eliminated by burning，so sepiolite could enduringly remove traces of HCHO in the air by intermittently thermal regeneration.