Ferromagnetic resonance experiments have been used to investigate the magnetic properties of amorphous $Co_{89.5}Zr_{10.5}$ thin films deposited by DC magnetron sputtering method. In the thickness range from $350;{AA}$ to $3,200;{AA}$, measurements were carried out in a static magnetic field perpendicular and parallel to the film plane and in a conventional 9.44 GHz spectrometer at room temperature. The ferromagnetic resonance spectra by the field perpendicular to the film plane showed standing spin wave. The spacing and the relative intensities between the various spin wave resonance peaks are analysed considering surface magnetic anisotropy. The surface magnetic anisotropy constant ($K_{so},;K_{sd}$) of amorphous $Co_{89.5}Zr_{10.5}$ thin films are $0.02;erg/ extrm{cm}^2$ and $0.55;erg/ extrm{cm}^2$ respectively regardless of the film thickness except for $3,200;{AA}$ film. In case of $3,200;{AA}$ these values are $0.46;erg/ extrm{cm}^2$ and $0.55;erg/ extrm{cm}^2$ respectively.