Abstract: The flow oscillation and large scale coherent structure in tight lattice in rolling motion is investigated theoretically with URANS.The calculation results are consistent with the experimental data.The rolling motion may have effect on the flow oscillation and coherent structure.The oscillation period in rolling motion is about ten percent bigger than that in steady state.The coherent velocity in rolling motion is a little different from that in steady state.The minimum coherent streamwise velocity is at the channel center,while the maximum coherent streamwise velocity is at the transition region of the channel center and narrow gap.However,the effect of rolling motion on the flow and heat transfer characteristics in tight lattice is limited.