  RV variable stars are important in astrophysics. The Large Sky Area
Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic survey has
provided ~ 6.5 million stellar spectra in its Data Release 4 (DR4). During the
survey, ~ 4.7 million unique sources were targeted and ~ 1 million stars
observed repeatedly. The probabilities of stars being RV variables are
estimated by comparing the observed radial velocity variations with the
simulated ones. We build a catalog of 80,702 RV variable candidates with
probability greater than 0.60 by analyzing the duplicate-observed multi-epoch
sources covered by the LAMOST DR4. Simulations and cross-identifications show
that the purity of the catalog is higher than 80%. The catalog consists of 77%
binary systems and 7% pulsating stars as well as 16% pollution by single stars.
3,138 RV variables are classified through cross-identifications with published
results in literatures. By using the 3,138 sources common to both LAMOST and a
collection of published RV variable catalogs we are able to analyze LAMOST's RV
variable detection rate. The efficiency of the method adopted in this work
relies not only on the sampling frequency of observations but also periods and
amplitudes of RV variables. With the progress of LAMOST, Gaia and other
surveys, more and more RV variables would will be confirmed and classified.
This catalog is valuable for other large-scale surveys, especially for RV
variable searches. The catalog will be released according to the LAMOST Data
Policy via http://dr4.lamost.org.
