In this study, we modeled the transmitted and reflected light of a phosphor layer in light-emitting diode packages by coupling the revised Kubelka-Munk and Mie-Lorenz theories. Through analyzing the transmitted and reflected light separately, it is found that the transmitted and reflected blue light vary monotonically with the changes of phosphor particle size, concentration and thickness. While the trends of the transmitted and reflected yellow light are non-monotonic, which are influenced by the interactions among the phosphor particle size, concentration and thickness. The light extraction efficiency through a phosphor layer was discussed. The reasons behind these phenomena were also presented.