In this paper, we report the changes in structural and dynamical properties of a MgSiO.sub.3 liquid under compression via molecular dynamics simulation. The short-range order is analyzed through the bond angles and bond lengths of the structural units, and the mean coordination number of both Si and Mg metals is found to increase with pressure. Intermediate-range order, characterized by the number of OT.sub.y links and of corner-, edge- and face-sharing bonds between two neighboring units, suggests the formation of Si-O- and Mg-O-rich regions in the magnesium silicate liquid. The self-diffusion and viscosity coefficients are then calculated to characterize the system dynamics and are found to be in good agreement with previous experiments and simulations. Most importantly, our result suggests a relationship between structural and dynamic heterogeneity of liquid magnesium silicates, particularly at high pressure. Graphical abstract