A novel sloping plate with wavelike surface was used to prepare semisolid alloy. Semisolid billets and slurries have been prepared by cooling or preheating the sloping plate. During preparation of the semisolid alloy by the proposed process, seed crystals derive from burst nucleation and breaking of dendrite and the coaction causes fine spherical microstructure formation. Casting temperature, sloping plate length, degree of cooling sloping angle are the main factors influencing the microstructure. Under current experimental conditions, in order to prepare good quality semisolid billets, proper casting temperature ranges of 660–690℃ for Al–3 wt-%Mg alloy and 660–680℃ for Al–6Si–2Mg (wt-%) alloy are suggested. The reasonable technological conditions for preparing Al–6Si–2Mg (wt-%) slurry are also proposed: the sloping plate preheating temperature is 300℃, and the casting temperature is 680℃. The optimum conditions for preparing semisolid billet of 1Cr–18Ni–9Ti stainless steel were obtained: the sloping plate length is 640 mm, and the casting temperature is 1600℃.