In the present study a solar water desalination system with humidification-dehumidification (HD) cycle is designed, integrating a solar still (as a solar humidifier) and a new subsurface condensation mechanism. Mass and energy balances are written for both solar humidifier and subsurface condenser in thermodynamic analysis of the system. Obtained nonlinear equations are analyzed numerically to explore the impact of the cycles parameters on fresh water production. The results of the analysis indicate that the rate of water production can reach above 264.86 (kg/day) and the produced water, passing through the pores on the tubes, can be used to irrigate plant roots or collected as drinking water. According to this design and numerical simulation, it is demonstrated that the new subsurface condensation can be a promising strategy for subsurface irrigation method; and the new mechanism allows farmers to use saline water for agricultural purposes by utilizing solar energy, particularly in arid areas.