The conformational, orientational and dynamical properties of single flexible ring polymers under simple shear flow are studied by a hybrid multiparticle collision dynamics simulation method. We found that contributing to the continuous stretching and constant alignment in the tank-treading motion, ring polymers undergo weaker deformation and orientation in the gradient direction, and show similar behaviors in the voracity direction compared with their linear analogues. We also present the mechanisms of both tumbling and tank-treading motions based on the time trajectories of relative deformation and orientation. Furthermore, the simulation results reveal that the special structures and unique dynamics of ring polymers in simple shear flow have an obvious influence on rheological properties, which are qualitatively different from the properties of linear polymers. (C) 2015 Elsevier Ltd. All rights reserved.