Strain localization is the precursor of the failure of frozen soil. So far， the research on strain localization of frozen soil is relatively weak. A micropolar elastoplastic numerical framework is established to simulate the strain localization of frozen soil by considering the effect of temperature. Through numerical simulation of plane strain test of frozen sand， it is found that the process of the generation， development and formation of shear bands of frozen soil can be simulated by the established numerical framework， and the stress-strain curve and shear band are in good agreement with the test results. Besides， the effects of temperature， end restraints and initial defects on the shear band are investigated. The angle and the width of the shear band increase with the decrease of temperature， and the specific failure mode and location of the shear band are closely related to the initial defects and end restraints. Through the simulation analysis for different finite element mesh， it can be observed that the simulation results obtained based on the coarse mesh are consistent with the fine mesh， which indicates that the mesh-dependent problem can be basically avoided.