[en] We report the results of angle dependent resistivity of NdFeAsO_0.82F_0.18 single crystals in the superconducting state. By doing the scaling of resistivity within the frame of the anisotropic Ginzburg-Landau theory, it is found that the angle dependent resistivity measured under different magnetic fields at a certain temperature can be collapsed onto one curve. As a scaling parameter, the anisotropy Γ can be determined for different temperatures. It is found that Γ(T) increases slowly with decreasing temperature, varying from Γ ≅ 5.48 at T = 50 K to Γ ≅ 6.24 at T = 44 K. This temperature dependence can be understood within the picture of multi-band superconductivity