In this paper an analitical investigation for performance analyses of a dehumidification wheel system with solid desiccant by the mathematical simulation of solid desiccant wheel and with the conservation of mass , energy and mumentum for the air flow and moiture content of desiccant bed in prossess air and regeneration air flow have been presented.Solid desiccant wheel have long been used in dehumidification and cooling systems. In this study a mathematical model has been derived to show the dehumidification trend of desiccant wheel. Four equation concerning water content balance and energy conservation and one momentum equation are used to describe the complicated heat and mass transfer and momentum occurring in moisture adsorption and regeneration. In this model, variation of several parameters such as air humidity ratio, air temperature, water content of desiccant bed and temperature of desiccant according to the length of bed and time were investigated. The mathematical model was confirmed by doing experimental tests on a solid desiccant wheel filled with silica gel. The results indicated that dehumidification rate during the length of desiccant Wheel depended mostly on input humidity ratio, air stream velocity, heat and mass transfer from air stream to bed. The results also described that air stream velocity was one of the most effective parameter on dehumidification rate of wheel.