  Xinglong Observatory of the National Astronomical Observatories, Chinese
Academy of Sciences (NAOC), is one of the major optical observatories in China,
which hosts nine optical telescopes including the Large Sky Area Multi-Object
Fiber Spectroscopic Telescope (LAMOST) and the 2.16 m reflector. Scientific
research from these telescopes is focused on stars, galaxies, and exoplanets
using multicolor photometry and spectroscopic observations. Therefore, it is
important to provide the observing conditions of the site, in detail, to the
astronomers for an efficient use of these facilities. In this article, we
present the characterization of observing conditions at Xinglong Observatory
based on the monitoring of meteorology, seeing and sky brightness during the
period from 2007 to 2014. Results suggest that Xinglong Observatory is still a
good site for astronomical observations. Our analysis of the observing
conditions at Xinglong Observatory can be used as a reference to the observers
on targets selection, observing strategy, and telescope operation.
