In this study, two kinds of melt-powder-melt-growth (MPMG) YBCO sample grown on a buffer layer of Y2O3 addition were fabricated. The compacted powders were located on a crucible with Y2O3 powder freely poured and a buffer layer of pressed Y2O3. AC susceptibility measurements of the samples as a function of temperature was reported for several different AC magnetic-field amplitudes (H (ac) ) in the presence of static bias magnetic field (H (b) ) directed along H (ac) . The loss peaks are found to shift towards lower temperatures as the AC field strength is increased. The frequency effect on the AC susceptibility was also measured. As the frequency increases, the peak temperature shifts to higher temperature. This effect can be interpreted in terms of flux creep.