The effect of magnet moving speed on the relaxation of the maximum levitation force of YBCO bulk has been investigated. The experiment was carried out between a cylinder permanent magnet and a single-domain YBCO bulk, and the levitation force was measured using a self-made levitation force measurement system. It is found that the levitation force decreases with time after the gap distance between the magnet and YBCO bulk reduced to 2 mm and kept for the test. It is also found that the levitation force and its relaxation rate is different for different moving speed between the magnet and the YBCO bulk, and the higher the moving speed, the greater the relaxation rate of levitation force. However, the largest levitation force is obtained at an optimal speed, the higher the levitation force, and the faster the relaxation of levitation force.