Abstract: In order to improve the thermoplasticity of lean duplex stainless steel, the precipitation law and mechanism of lean duplex stainless steel 2101 (LDX2101) and duplex stainless steel 2205 (DSS2205) were studied in hot rolling. It is found that LDX2101 is susceptible to nitride precipitation at phase boundaries compared with DSS2205, which causes microcracks and results in the thermoplasticity of specimens worsen. According to relevant thermodynamic data, the equilibrium solid solubility formulas of Cr₂N precipitation in LDX2101 and DSS2205 were deduced, and total solid solution temperatures of Cr₂N precipitation were calculated through Thermo-Calc software and experimental data. Meanwhile, the Wagner interaction coefficient was introduced to consider the influence of Ni, Mn, Mo and Si on the equilibrium solid solubility product formula. The results show that the total solid solution temperature of Cr₂N precipitation in LDX2101 is around 100 ℃ higher than that in DSS2205. The calculation results and experimental results are in good agreement. The finishing hot roiling temperature must be above the total solid solution temperature in the practical production process to prevent Cr₂N precipitation. Otherwise, the nitride precipitation is prone to produce at phase boundaries, which influences the thermoplasticity of the materials.