Based on the collection and selection of the parameters of water molecules and hydrogen bonds, configurations of a minimum ice structure unit (MISU) and ice crystal were simulated step by step thanks for the AutoCAD software. The simulation indicates that a minimum ice structure unit is made up of 10 H2O molecules in a four-hexagon cage structure. Based on the simulation, 1 mole of ice crystal contains 2 mole of hydrogen bonds, and 16.7% of hydrogen bonds (5.86 kJ•mol－1), 12.5% of hydrogen bonds (4.40 kJ• mol－1) and 70.8% of hydrogen bonds (24.94 kJ•mol－1) should be broken during the processes of ice fusion at 0 ℃, water calefaction from 0 to 100 ℃, and water vaporization at 100 ℃ respectively. The fusion and vaporization enthalpy values of water are 0.15 and 15.73 kJ•mol－1, which are consistent with the values of hydrides of Group VIA (H2O, H2S, H2Se, H2Te). Density of ice 923.17 kg•m－3 increased to that of water 999.89 kg•m－3 during ice fusion at 0 ℃, which could also be calculated based on the MISU simulation.

Key words: minimum ice structural unit (MISU), hydrogen bond, simulation, quantitative analysis