The cavity ring-down method has an extremely high measurement sensitivity to the absorption of a medium in the cavity and can be used to accurately measure cavity loss. Based on the theories of free carrier absorption and resonant cavity, this study establishes a theoretical model of an optical cavity ring-down to measure the properties of semiconductor materials and derives the functional relationship among the cavity ring-down signal, semiconductor material characteristic parameters, and cavity structure parameters. Simulation analysis and experimental verification are performed. Simulation results show that the cavity ring-down method can be used to accurately measure semiconductor material properties, such as doping concentration and resistivity. Meanwhile, based on the proposed method, the doping concentration and resistivity of a crystalline silicon wafer are determined experimentally to be $(\mathrm{2.65}\pm \mathrm{0.38})\times {\mathrm{10}}^{\mathrm{16}}\mathrm{c}{\mathrm{m}}^{-\mathrm{3}}$ and $(\mathrm{0.61}\pm \mathrm{0.07})\mathrm{\Omega }?\mathrm{c}\mathrm{m}$ respectively, exhibiting the high application potential of this method for measuring semiconductor material properties.