By improving the method of glass denucleating combined with cycle superheating based on traditional undercooling method, a stable undercooling above 200 K of 100g bulk K4169 is obtained, and the largest undercooling goes to 281 K. The effect of denucleating agent and superheating have been discussed. Moreover, the three-dimensional numerical analysis of temperature field inside the undercooled melt is presented, it can be found that the maximum temperature deviation in different parts is only 14K before nucleation. In contrast with the as-solidified microstructure, the grain size will increase with the increment of nucleating temperature. But the difference of microstructure is tiny and the average grain size is 12?2 μm.