The objective of this study to explain the effect of potassium sorbate  E 202 (0.1%, 0.2% and 0.3%) on some chemicals properties )Moisture, Acidity, Salt, Fat, pH, Total nitrogen and Soluble nitrogen), microbiological properties (Total Bacteria count, Total count of fungi and yeast and its effect on fungal growth and mycotoxins production) of Ras cheese during five ripening periods (fresh, 15 days, 30 days, 60 days, 90 days) and  sensory evaluation for cheese in (30 days, 60 days and 90 days). The results show that moisture and pH decrease in all treatments during ripening period's progress, Acidity, T.N and S.N increases in all treatments as the settlement period progresses, and the highest was in the second treatment (Ras cheese treated with 0.2% potassium sorbate). Results showed a good role of potassium sorbate in inhibiting fungal growth by increasing its concentration and its role in inhibiting the ability of fungi to produce mycotoxins. Cheese treated with potassium sorbate 0.3% had the best sensory acceptance during the ripening period (60 days), with a rate of 96.5% that mean that it can use potassium sorbate as a good antifungal factor to improve Ras cheese quality.