Abstract: The amorphous SmDyFeCo magnetic-optical thin films are r.f. -magnetron sputtered onto glass substrate. The influences of sputtering argon pressure and power on the magnetic properties of the amorphous SmDyFeCo thin films are investigated. It is shown that when compared with the amorphous DyFeCo thin film, the coercivity Hc of the amorphous SmDyFeCo thin film changes more slowly with temperature, and it has larger magnetic perpendicular anisotropy and Kerr angle at short wavelength. Therefore, it can be used as a practical magneto-optical recording medium.