Duplex stainless steels (DSSs) were processed to have a balanced microstructure containing approximately equal amounts of ferrite and austenite, which exhibit exceptional mechanical properties and corrosion resistance. Lean duplex stainless steel (LDX) 2101 with lower contents of Ni and Mo had been developed in order to further reduce the cost. The coexistence of ferrite and austenite during hot deformation led to a complicated deformation behavior. However, little research had been dedicated to studying the microstructure evolution in LDX 2101 compared with traditional DSSs. In addition, the reported results of microstructure evolution both in ferrite and austenite phases of traditional DSSs exhibited obvious controversy. In the present paper, the microstructure evolution of the LDX 2101 during hot compression at a strain rate of 5 s⁻¹ and 1000 ℃ was studied by electron backscatter diffraction (EBSD) together with TEM. The results showed that continuous dynamic recrystallization (CDRX) occurred both in ferrite and austenite phases by gradual transformation of ow angle grain boundary into high angle rain boundary. In addition, a large number of Σ3 twins appeared after solution anneaing treatment. The hot deformation resulted in a progressive disappearance of the Σ3 twin boundaries in austenite phase. Flow curve characteristics of the LDX 211 during hot deformation were interpreted by the coupling behaviors of the microstructure evolution of its both phases.