To explore the thermal performance of prefabricated extruded cement panel(ECP), 15 finite element models were built using three steel column forms and five sandwich insulation materials as parameters. According to the simulation results, the influences of the parameters on the thermal performance of the ECP composite wall were analyzed. On this basis, the external insulation measures were taken, and the thickness of the insulation layer was 050mm, and the wall inner surface temperature distributions in the thermal bridge of steel column was obtained. The results show that the heat transfer coefficient of ECP composite wall is 02260319W/(m2·K), which is lower than the limiting value of 035W/(m2·K) in the standard for freezing and cold area. When the external thermal insulation measures are applied to the steel column, the inner surface temperature of ECP composite wall increases, the influence range of the thermal bridge decreases, and the thermal insulation performance is significantly improved.