Abstract: Since all of the fuzzy knowledge in the general fuzzy rough set models can result in uncertainty of the weak fuzzy partitions of the universe of a fuzzy set, a further extended study is done to find out more about the fuzzy rough sets. A new optimized fuzzy rough set model is constructed by use of the relationship intensity between the decision-making fuzzy eventFand fuzzy conditional eventΦ.then the upper and lower approximate operator of the fuzzy set are determined so that the possibility degree and the inevitability degree of an object belonging to a fuzzy set is maximal and the expression is the optimal approximation