By using self-made vibrating wavelike sloping plate setup, semisolid billets with fine spherical or rosette grains have be prepared by semi-continuous casting, and the solidified shell on the sloping plate surface can be effectively avoided. Burst nucleation in the whole melt and dendrite fracture causes the formation of fine spherical microstructures. Under the current experimental conditions, proper casting temperature ranges of 660°C~680°C and the amplitude value of under 2mm proper are suggested. When the reheating temperature is 575°C and the holding time is 60min for AZ91D alloy, 597°C and 90min for Al-6Si-2Mg (wt-%) alloy, semisolid forging process can be successfully implemented. Thixo-forming products of two alloys are fine with smooth appearance, good microstructures and properties.