In this paper, a solar desalination system with humidification-dehumidification cycle consisting of a solar humidifier and a subsurface condensation mechanism designed for producing fresh or irrigation water is studied and numerically simulated. In this system, solar energy is used for providing the required heat and a set of tubes buried in the soil are used as condensers. Initially, in order to increase inflowing air humidity, seawater or any other brackish water is vaporized in a solar humidifier and then the humid air is passed through a set of tubes buried in the soil. Then the condensation mechanism takes place and fresh water is produced. Mass and energy balance equations for solar humidifier and subsurface condenser are used for thermodynamic analysis. The resulting linear and nonlinear equations are numerically solved for analyzing different parameters of the cycle and determining the amount of water produced. Finally, the sensitivity of the cycle's primary parameters was analyzed using design of experiment (DoE) method based on response surface method (RSM) in order to obtain optimal conditions. In addition different diagrams are presented to assist the designer to choose suitable design parameters based on the operational conditions. According to the design and numerical simulation, the rate of fresh water produced per underground pipe's length is 3.812153(kg/m.hr). (C) 2016 Elsevier B.V. All rights reserved.