The observations of solid-liquid interface morphology of InSb single crystals pulled by using various oriented seeds is described. Experimental results indicate that the external forms of crystals as well as the formation of growth twin are closely related to the development and properties of 111 facets on the solid growth surface. The various experimental phenomena can all be interpreted successfully according to a 111 plane octahedron or two-octahedron model of the zinc-blende structure.