The classical one-dimensional solute segregation theory of BPS is extended to two dimensions, i.e., axial as well as radial dimensions. By solving the two-dimensional boundary value problem at steady state, an analytical expression of solute concentration distribution near crystal/melt interface is approximated. The new effective segregation coefficient is consequently derived as k e = k e B P S -(k e B P S -k 0 )(r/R c ) λ β , which decreases with the relative radial distance r/R c , as compared to the constant k e B P S from the one-dimensional BPS theory. The rate of decrease depends on the power factor λ/β = λ D L R c /Uδ 2 . Since it relates the solute segregation with the lateral flow strength U and the crystal radius R c , the new model overcomes the weaknesses of the BPS model and gives explanations on both normal and lateral solute segregation phenomena.