  Since September 2018, LAMOST starts a new 5-year medium-resolution
spectroscopic survey (MRS) using bright/gray nights. We present the scientific
goals of LAMOST-MRS and propose a near optimistic strategy of the survey. A
complete footprint is also provided. Not only the regular medium-resolution
survey, but also a time-domain spectroscopic survey is being conducted since
2018 and will be end in 2023. According to the detailed survey plan, we expect
that LAMOST-MRS can observe about 2 million stellar spectra with ~7500 and
limiting magnitude of around G=15 mag. Moreover, it will also provide about 200
thousand stars with averagely 60-epoch observations and limiting magnitude of
G~14 mag. These high quality spectra will give around 20 elemental abundances,
rotational velocities, emission line profiles as well as precise radial
velocity with uncertainty less than 1 km/s. With these data, we expect that
LAMOST can effectively leverage sciences on stellar physics, e.g. exotic binary
stars, detailed observation of many types of variable stars etc., planet host
stars, emission nebulae, open clusters, young pre-main-sequence stars etc.
