Abstract: The thermodynamics such as dissolve and melt process of nano-material is different from bulk material because of fine size and high interfacial energy of nano-material. The relations between element equilibrium solution product, melting point and size of nano-particle have been deduced. Results show that element equilibrium solution product increase and melting point drop down gradually with the decrease of nano-particle size. The change of equilibrium solution and melting point increases with the variation of nano-particle size. Calculations show that increment percent of element equilibrium solution product is 11.71% of radius 0.1nm Al 2O3 than bulk Al₂O₃ that 0.01% mass in liquid iron. The melting points of radius 1nm Al₂O₃ are respectively 1849K and 1267K in the atmosphere and liquid iron. The decrement of melt points are respectively 454K and 1036K.