A molecular-dynamics simulation is carried out to study the changes in statistical geometry and related dynamical properties in the Li2SiO3system at the glass transition point. The number of oxygens around each cation within the first coordination shell is taken as the numberVof vertices of the polyhedron that characterizes the system. When the numberNof O-O pairs that are shorter thanRO(ROis the position where the second plateau of the running coordination numbernO-O(r) ends) is counted, the distribution ofNis found to have a maximum atN= 3V- 6 (V= 3, …, 7) below the glass transition temperature.Ncorresponds to the number of contact pairs in each polyhedron. The lifetime of the polyhedron withN= 3V- 6 is found to be longer than other polyhedra with other values ofN. The results suggest that geometrical degrees of freedom play an important role in glass formation in this system.