Abstract: Based on the research of a covering rough set model, the definitions about the upper approximation of the covering rough set are found to be inconsistent. Through the analysis of the difference among the several models, a more reasonable model is adopted, and, combined with the theory about covering reduction, the covering rough set model is redefined. Its several properties are given. Meanwhile, the model is extended, and the covering rough fuzzy set model is defined. Then some of its good properties are also proved.