Abstract: The YBaCuO bulk material with large superconducting domains was fabricated using MTG SmBaCuO superconductive crystal as a growth seed. The strong flux pinning and well intergrain linking could be drawn from the investigations on D.C. and A.C. magnetizing behaviours. The strong flux pinning made it possible for the YBCO bulk with large domain to capture a great deal of flux after the the applied field was removed, and such a bulk sample showed a good quasi- permanent magnet characteristics, The residual magnetic field intensity H_rem was measured to be 0.125T after a large YBCO bulk was magnetized in several minutes under a NdFeB permanent magnet with surface field of 0.5T. And we did not find the evident degradation of H_rem in a short time.