Grain boundary motion in the presence of grain boundary segregation was investigated by means of phase field simulations. It was found that the solute concentration at the moving grain boundary might increase with increasing velocity and became larger than the equilibrium value, which was unexpected according to the solute drag theory proposed by Cahn, but was observed in some experiments. A non-linear relation between the driving force (curvature) and the grain boundary velocity was found in two cases: (1) the grain boundary motion undergoes a transition from the low-velocity extreme to the high-velocity extreme; (2) the grain boundary migrates slowly in a strongly segregating system. The first case was consistent with the solute drag theory of Cahn. As for the second case, which was unexpected according to solute drag theory, the non-linear relation between the grain boundary velocity and curvature comes from two sources: the non-linear relation of the solute drag force with grain boundary velocity, and the variation in grain boundary energy with curvature. It was also found that, when the diffusivity was spatially inhomogeneous, the kinetics of grain boundary motion was different from that with a constant diffusivity. Phase Field Modelling of Grain Boundary Migration with Solute Drag. J.Li, J.Wang, G.Yang: Acta Materialia, 2009, 57[7], 2108-20