The system of (Al2O3)2(SiO2) [AS2] consists of 1650 atoms was simulated by the molecular dynamics simulation method with the Born-Mayer type pair potentials. The system has been studied at a pressure of 0 GPa, the temperature of system was changed 300, 1000, 2000, 3000, 4000, 5000 K. Microstructures and diffusion properties of AS2 has been ivestigated by calculating the parameters of the microstructures and diffusive constanst under certain pressure values. Dynamic viscosity of atomics is also calulated and discussed.