Constitutive modeling of CoCrFeMnNi high-entropy alloy (HEA) at cryogenic temperature (77 K) and room temperature(293 K) has been investigated. The effect of temperature on deformation behavior such as twinning, forest hardening, andback stress hardening has been established. The enhanced ductility and strength of CoCrFeMnNi HEA at 77 K are duethe combination of sub-grain structure, twinning, and dislocations. This phenomenon is explained in terms of quantitativevalues of twin volume fraction, inter-twin spacing, and dislocation density. The isotropic kinematic constitutive model isconstructed with a critical twinning stress parameter to obtain the criteria for twinning initiation. The developed finite elementmodel simulation results at 77 K and 293 K are in good agreement with the experimental data. The model displays asmooth increase in the twin volume fraction until fracture point (maximum twin fraction region). Also, different modelingparameters are obtained for each temperature to account for the changing deformation behavior.