We introduce the structure and the capability of a UHV x-ray scattering system constructed for surface structural studies. The system consists of vacuum parts required for surface preparation and a vertical-horizontal diffractometer using the S2D2 geometry. To illustrate the capability of the system, we measured the 7$ imes$7 reconstruction peak of a Si (111) surface. The peak count rate was 216 counts/sec and the domain size of the 7$ imes$7 reconstruction was larger than 1600 $AA$. This demonstrates that the system is capable of providing surface structural information.