The one side leaky wave technique is discussed for determination of the refractive indices n o , n e and thickness d of the anisotropic polymer thin film through the measurement of the coupling angles corresponding to leaky modes, and the calculation of their effective indices and solving the corresponding mode equations. The results of measurement and calculation for PT PEK c film are: n o =1.6525±0.0014, n e = 1.6439 ±0.0019, d=2.33±0.32 μm.