Abstract With about 12,000 OB type stars selected from the LAMOST and Gaia survey, we study their 3 dimensional velocity distribution over the range of galactocentric radius from 6 to 15 kpc in the Galactic disk plane. A clear ripple pattern in the radial velocity ($V_R$) map is shown. The median $V_R$ reaches $-8$ km s$^{-1}$ at $R\sim9$ kpc, then increases to $\sim0$ km s$^{-1}$ at $R\sim12$ kpc, and later declines to below $-10$ km s$^{-1}$ beyond $R\sim13$,kpc.