Using air as a carrier gas is common in humidification-dehumidification desalination processes. A computer program was written using mass and energy balances for model in the process behavior. The parameters considered in this work were inlet air and fresh water recycle temperatures, inlet air flow rate, saline water and fresh water recycle flow rates, and saline water to airflow ratio. Results of simulation showed that increasing inlet air and fresh water recycle flow rate increases fresh water production. It was also found that heating the inlet air to humidification column or cooling the inlet water to dehumidification column increases the production rate but increasing water to air flow ratio in a humidifier leads to a lower production rate. The predicted effects of the parameters on fresh water production agreed well with the existing experimental data.