Hot-compression experiments of 316LN stainless steel have been conducted on a Gleeble-1500D thermal-mechanical simulator. We have analyzed the flow stress-strain curve and acquired the constitutive equation of 316LN steel by calculating stress exponent, activation energy and Zemer-Hollomon parameter. Then, based on the material model theories and Prasad instability criterion, the iso-efficiency map at strain 0.6 of 316LN steel has been developed. The larger power dissipation rate is emerging at 1050~1200°C and lower strain rate. In addition, we have also analyzed the hot deformation microstructure mechanism of 316LN steel is discontinuous dynamic recrystallization by the observation of deformation microstructure. These results have been of great significance to understand microstructure evolution and to determine the optimum hot-working conditions in the production.