With the rapid development of the manufacturing industry, titanium tubes are developing in the direction of thin-walled and lightweight, and the demand for large-size thin-walled titanium tubes has increased dramatically. However, titanium alloy material processing temperature range is narrow, difficult to control the organizational properties, deformation resistance, etc. lead to large-size thin-walled titanium tube forming manufacturing faces great challenges. In this paper, Abaqus software is used to numerically simulate the tube expanding process of large-diameter thin-walled tubes (Φ426mm×16mm), and to study the effects of stress and strain fields and process parameters on the expanding process during the hot tube expanding process. It was found that the distribution of equivalent stress in the hot tube expanding process was similar to that of axial stress; the circumferential stress showed obvious differences along the wall thickness. As the friction coefficient between the inner wall of the tube and th