Transparent conductive oxides are widely used in photovoltaic devices and flat panel displays. The knowledge of the dielectric function is essential for the application of transparent conducting oxide thin films. The La2/3Sr1/3VO3 (LSVO) thin film was successfully prepared on (LaAlO3)0.3(Sr2AlTaO6)0.35(LSAT) substrate by pulsed laser deposition. The optical properties of the LSVO thin film was measured by spectroscopic ellipsometry. The dielectric function of the LSVO thin film is described by B-spline model and Lorentz+Tauc-Lorentz dispersion model, respectively. The results showed that there are two significant optical transitions located at 3.41 eV and 4.11 eV in the visible region. The red shift of the optical bandgap in the doped LSVO thin film, which is located at 3.41 eV, is about 0.19 eV. The transition (positioned at 4.11 eV) in the high energy region is attribute to the charge transfer excitation involved in O 2p orbital and the upper unoccupied V 4 s orbital.