Oasis houses are known for their sensitive architectural response to the region's climatic conditions and socio-cultural norms. Courtyard is one of the invariants in oasis architectural forms that contributed in determining climatic, physical and psychological interior environment. Given its effectiveness as an interior micro climatic regulatory element, the daylight behavior of the courtyard in this type of houses is one of the most important passive strategies that can affect the nature of activities and the use of space in a daily manner, Without having to use the interior spaces to do various tasks. In this respect, this article presents an experimental study carried out to clarify the impact of the courtyard on visual efficiency of oasis houses located in the city of M'chouneche (Biskra), using simulation software on model of a real house. The simulation process was carried out at solstice days and spring equinox, taking into account the climatic data of the city of M'chouneche. The experimental results confirm that the obtained quantity of daylight in the most of interior spaces no matter it is not compatible with the required values, gives certain balance with the life style of occupant and the use of courtyard its self.