  LAMOST-MRS-B is one of the sub-surveys of LAMOST medium-resolution (R~7500)
spectroscopic survey. It aims at studying the statistical properties (e.g.,
binary fraction, orbital period distribution, mass ratio distribution) of
binary stars and exotic stars. We intend to observe about 30000 stars (10 mag
<= G <= 14.5 mag) with at least 10 visits in five years. We first planned to
observe 25 plates around the galactic plane in 2018. Then the plates were
reduced to 12 in 2019 because of the limitation of observation. At the same
time, two new plates located at the high galactic latitude were added to
explore binary properties influenced by the different environments. In this
survey project, we set the identified exotic and low-metallicity stars with the
highest observation priorities. For the rest of the selected stars, we gave
higher priority to the relatively brighter stars in order to obtain
high-quality spectra as many as possible. Spectra of 49129 stars have been
obtained in LAMOST-MRS-B field and released in DR8, of which 28828 and 3375
stars have been visited more than twice and ten times with SNR >= 10,
respectively. Most of the sources are B-, A-, and F-type stars with 0.6 <
[Fe/H] < 0.4 dex. We also obtain 347 identified variable and exotic stars and
about 250 stars with [Fe/H] < 1 dex. We measure radial velocities (RVs) by
using 892233 spectra of the stars. The uncertainties of RV achieve about 1 km/s
and 10 km/s1 for 95% of late- and early-type stars, respectively. The datasets
presented in this paper are available at
http://www.doi.org/10.57760/sciencedb.j00113.00035.
