This catalog provides radial velocity (RV) measurement for 1,594,956 spectra (each spectrum has two wavebands) of the LAMOST-II medium resolution (R~7500) survey. Employing a set of RV standard stars, the zero-point of the measurement have been calibrated. Some reference RV datasets derived from medium/high-resolution observations have been used to evaluate the accuracy of the measurement. Comparing with reference sets, the accuracy of our measurement can get 0.0227 km/s to radial velocities standard stars. The intrinsic precision is estimated with the multiple observations of single stars, which can achieve to 1.36km/s, 1.08 km/s, 0.91 km/s for the spectra at signal-to-noise levels of 10, 20, 50, respectively.