Semi-solid slurry was prepared by pouring A356 superheated melt with different temperature with electromagnetic stirring into a hot mold at 550℃. Microstructure of the prepared slurry was observed by OM （ optical microscope） and Image-Pro Plus software to understand the solidification behavior of aluminum alloy A356 superheated melt during pouring process. The results indicate that primary α-Al phase exhibits developed dendritic structure in the slurry with pouring at 710 ℃ as a result of low nucleation rate. Primary phase is converted gradually from dendrite into non-dendrite with pouring at 670 ℃ due to the great increase of effective nucleation rate in the melt. Microstructure with about 60% non-dendrite in the primary phase can be obtained with pouring at 630 ℃

in which non-dendrite with about 30 μm in size and 1.35 in roundness can be observed.