Abstract: As an important cosmic distance indicator, the RRab Lyrae star (RRab) plays a significant role in studying the dynamical properties of the Milky Way. However, due to the pulsation characteristics of RRab, their radial velocities include not only heliocentric velocities but also pulsation velocities, which poses a challenge for precise measurements. This study utilizes the Mg Ib line and \rmH\alpha line from the medium-resolution spectra in Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to establish radial velocity curve templates for RRab, aiming to enhance the precision of heliocentric radial velocity measurements. Comparative analysis with existing templates indicates that the radial velocity curve templates in this study exhibit high consistency in radial velocity estimation, and the standard deviations of the heliocentric radial velocities calculated based on the radial velocity curve templates established in this paper are less than 5 \textkm \cdot \texts^-1. The radial velocity curve templates established in this study are applicable for calculating the heliocentric radial velocities of RRab from the LAMOST spectra.