As a self-insulating building material which can meet the 65 percent energy-efficiency requirements in cold regions of China, aerated concrete blocks often go moldy, suffer frost heaving, or cause plaster layer hollowing at thermal bridge parts in extremely cold regions due to the restrictions of environmental climate and construction technique. Outer-corner part and T-shaped part of aerated concrete walls are most influenced by thermal bridge effect. In this paper heat transfer calculation models for outer-corner wall and T-shaped wall were developed, and their temperature fields were simulated. According to the simulation results, insulation measures of the thermal-bridge position of self-heat-insulting walls were designed to weaken or even eliminate thermal bridge effect and to improve the temperature of thermal-bridge position. And the influences of the thickness and location of the local insulation layer on the temperature field were analyzed. Consequently, the condensation inside self-thermal-insulating wall and frost heaving caused by condensation and low temperature were reduced, avoiding damage to the wall body from condensation. The research results can provide theoretical basis for the application and extension of self-thermal-insulating wall in extremely cold regions.