Abstract： The effect of ultrasonic atomization liquid desiccant dehumidification system (UADS) on indoor air quality was studied in this paper. The safety threshold of lithium chloride in indoor air was proposed to be 70μg/m3. Besides, the influence of inlet mass fraction of LiCl (wi) and mesh mist eliminator porosity on carryover was experimentally studied and analyzed. Results show that when the wi rises from 31.5% to 38.8%, the carryover increases to 26.93μg/m3. In addition, the porosity of mesh mist eliminator affects carryover significantly, porosity lower than 93.5% is safe. However, carryover is lower than the safety threshold even under the most unfavorable condition, it manifests UADS cannot affect indoor air quality. The result of this study provides some practical information for application of UADS.