In semi-solid forging, it is necessary to control the forming variables accurately in order to make near net shape products. Generally, the defects of products may occur due to liquid segregation that can be caused by deformation, strain rate, and condition of friction. The liquid segregation is to be predicted by flow analysis. This paper presents upper bound analysis model using the new yield function proposed by Doraivelu et al. The model has been applied to analyze the simple compression process of semi-solid Sn­-15%Pb alloys to confirm the usefulness of the yield function. The radial distribution of the liquid fraction at various strains, strain rates, and friction conditions between die and workpiece has been estimated.