In order to investigate the dissolution mechanism of chloride in the desalination process of sea sand, desalination experiments were conducted by different methods to analyze the relationships of the amount of dissolved chloride with time and water-sand mass ratio. Based on the distribution and dissolution characteristics of chloride in sea sand, a chloride dissolution model considering both the surface chloride solution and the internal chloride dissolution was developed, from the dissolution and diffusion theory derived from the Fick's law. The results of model validations show that this model can well describe the chloride dissolution process and reflect the influences of time and water-sand mass ratio on the desalination effect of sea sand.