  With a sky brightness monitor in Xinglong station of National Astronomical
Observatories of China (NAOC), we collected data from 22 dark clear nights and
90 lunar nights. We first measured the sky brightness variation with time in
dark nights, found a clear correlation between the sky brightness and human
activity. Then with a modified sky brightness model of moon night and data from
moon night, we derived the typical value for several important parameters in
the model. With these results, we calculated the sky brightness distribution
under a given moon condition for Xinglong station. Furthermore, we simulated
the moon night sky brightness distribution in a 5 degree field of view
telescope (such as LAMOST). These simulations will be helpful to determine the
magnitude limit, exposure time as well as the survey design for LAMOST at lunar
night.
