Abstract: In this paper the growth processes of AI-Si eutectic modified by strontium are discussed. Systematic analysis on theoretical calculations and experimental results shows that the undercooling AT caused the solute diffusion in liquid and the Gibbs-Thompson effect is only a small part of the total undercooling at the solid-liquid interface on which the eutectic growth velocity and temperature gradient have important influence.It is thought that the growth of modified AI-Si eutectic is a process being located at a stable non-equilibrium thermodynamical condition. The process is mainly caused from the selection of eutectic silicon to fibre-like morphology, for which a large kinetic undercooling is required.It is also shown that for unidirectional growth raising the temperature gradient increases eutectic spacing and decreases kinetic undercooling of modified Al-Si eutectic.