Wadi Al-Quwayiyah, Riyadh Region, Saudi Arabia, is one of the most important Wadis of the Kingdom. The current study aimed to determine floristic composition, the structure of the vegetation, and species distribution at four different plant communities in Wadi Al-Quwayiyah, Riyadh Region, Saudi Arabia, and highlighting the ecological factors that affect species distribution. The study revealed forty-two plant species belonging to 21 families were collected and found to be dispersed over four different plant communities: Acacia tortilis, Leptadenia pyrotechnica, Zizuphus nummularia, and Acacia gerradii. Leguminosae and Brassicaceae were the dominant families, and therophytes and chamaephytes and were predominant life forms, which demonstrate a typical desert life-form. Soil texture, organic matter content, Na, CaCO₃, Cl, Ca, Mg, pH and EC were the primary parameters affecting the occurrence of plants. Perennials accounted for 28 of the total reported species in this survey about 66.7% of the listed species. Annuals, on the other hand, accounted for 14 species (33.3%).