The change regulation of the sinter hightemperature compressive strength was studied by a high temperature compressive testing machine with adjustable atmosphere. The experimental results show that the compressive strength of the sinter fell with the rising of temperature before reduction, but fluctuated with temperature and reduction degree after reduction, and there was a linear relationship with its porosity rate. Finally the sinter damage mechanism under normal temperature and high temperature during smelting in blast furnace is analyzed with the experimental results.