Abstract: The gap and friction between the tube and the tools are important contact boundary conditions in the tube rotary draw bending process. The influence of the gap and friction between different tools and tube on the quality of large-diameter thin-walled steel tube during the bending process was studied by numerical simulation and experiment. The results show that the numerical simulation is in good agreement with the experimental results, and the relative error of the inner wall thickness is less than 10%. With the increase of the tube/bending die gap, the tube/wiper gap and the tube/mandrel gap, the outer wall thinning rate gradually decreases, while the cross-section distortion gradually increases. The gap between tube and mandrel plays an important role in wrinkling. With the increase of friction coefficient between the tube and wiper, the cross-section distortion increases gradually, however, it has no significant effect on the outer wall thinning and inner wrinkling. With the increase of the friction coefficient between the tube and mandrel, the outer wall thinning and wrinkling all gradually increase, the friction coefficient should be less than 0.15 in the rotary bending forming. The research results are helpful for the determination of the contact boundary condition during thin-wall tube rotary draw bending.