A solid phase of a fatty acid mixture (lauric acid + myristic acid) on a rotating cold cylinder from the binary melt was formed in an annular cylindrical vessel. The growth rate of the solid phase was kept constant by cooling the rotating cold cylinder. The shape of the solid phase formed on the rotating cold cylinder depended on the hydrodynamics of Taylor vortices in the melt phase. The solid phase consisted of a concave part and convex part. We observed the detail structures of the surface and the inside of the solid phase under a microscope, and analyzed the crystallinity of the solid phase by using X-ray diffraction. We measured the weight fraction of myristic acid from the thin slices of the solid phase by gas chromatography. The growth rate of the solid phase decreased as the rotation speed increased or as the temperature of the hot cylinder increased. When the growth rate decreased, the crystalline part of the solid phase obviously increased. The effective distribution coefficient of lauric acid between the solid phase and melt phase increased according to the crystalline of the solid phase. The effective distribution could be well correlated with the growth rate by using our interfacial distribution model.