Polar anchoring energy of a dye-doped liquid crystal (DDLC) cell is determined based on capacity measurements. Experimental results indicate that under the illumination of a pump beam, the polar anchoring energy (7.90×10−6 J/m2) includes the adsorption-induced anchoring energy (5.74×10−6 J/m2) and the preexisting-dye-induced anchoring energy (2.16×10−6 J/m2). The latter is attributed to the torque, which is induced by the dye molecules on the boundary surface even before illumination. After the illumination, the adsorption-induced anchoring energy remains and the preexisting-dye-induced anchoring energy disappears, with the former revealing that weak anchoring affects the decay time and threshold voltage of the DDLC cell. Moreover, plotting the polar angle distributions in the DDLC cell reveals its correlation with variations in the capacitance of the DDLC cell.