The cooperative up-conversion blue luminescence of Yb3+ ion-doped oxyfluoride vitroceramic material (Yb:FOV)and the influence of co-doped Ho3+ ion, when excited by a 960 nm diode-laser, are studied in this paper. A strong blue 479.1 nm up-conversion luminescence of the Yb:FOV material is discovered. It is found that the 479.1 nm luminescence results from the cooperative up-conversion of the coupled states of the Yb3+-Yb3+ clusters formed by two adjacent Yb3+ ions. The measured cooperative up-conversion luminescence main peak 479.1 nm of this paper is different from the characteristic fluorescence main peak of the Tb3+ ion positioned at about 495-504nm wave-range. Our result coincides with all the published correct papers, whose cooperative up-conversion luminescence main peaks of the direct Yb3+-Yb3+ clusters are all positioned at about 476-480 nm wave-range. All of these indicate that the large cooperative up-conversion blue luminescence of the direct Yb3+-Yb3+ clusters discovered in this paper is stable.