A theoretic model is developed to describe the moisture desorption-and-adsorption cycle of silica gel dehumidification system with or without ultrasonic-assisted regeneration. The model has been validated by a series of experiments. The AMRC (additional moisture removal capacity) and the DCOP (dehumidification coefficient of performance) are suggested to illustrate the performance of silica gel dehumidification system with ultrasonic radiation. The effects of ultrasonic-assisted regeneration on the performance of the dehumidification system are investigated with the model under different conditions. Some crucial conclusions have been drawn from the simulation results, e.g., the higher regeneration temperature is conducive to increasing the AMRC; the higher ambient air temperature is conducive to increasing the AMRC and DCOP of the system; the higher ambient air humidity level will result in the bigger AMRC and the lower DCOP of the system; the higher initial moisture ratio of silica gel is in its favor for improving the DCOP, but unfavorable for increasing the AMRC; the optimal regeneration time aiming at the maximum AMRC or DCOP decreases as the regeneration temperature or the air velocity increases. And it increases as the ambient air temperature or humidity or the initial moisture content of silica gel increases. (c) 2014 Elsevier Ltd. All rights reserved.