Solute distribution and segregation in solidification will largely influence the characteristics of solidification microstructure and precipitation order of the second phase. In this paper, the solid-liquid interfaces of Mg-6Al alloy with different temperature were obtained by rapid quenching based on a special melting furnace and were analyzed using scanning electron microscopy, energy diffraction spectrum and Thermo-Calc calculation tool. It was found that the primary α-Mg phase grew through cystiform dendrite interface. The solute partition coefficient and dendrite segregation rate for Al in the solid phase of Mg-6Al alloy basically had little change with decrease of the temperature. The dendrite become fine, and the solute partition coefficient decreased, while dendrite segregation rate of Al in the dendrite boundaries increased, because of the addition of Zn to Mg-6Al alloys.