The breakage of checker brick in regenerator of the coke oven is associated with high content of impurities such as Fe2O3,K2O and so and.The used semi-silica brick composition analysis showed that the increasing amplitude of Fe2O3 and K2O are lower than fireclay brick.The main compositions of the used fireclay brick and semi-silica checker brick are kaoline, glasses phase, mullite and magnesium aluminum titanium iron oxide based precipitation phase.The Fe2O3 content in matrix phase and precipitation phase is high.The solid solution of K2O with kaoline phase reduces the melting point of check brick and the brick performance.Fe2O3 and CO undergo repeated oxidation-reduction reactions with checker bricks during the heat exchange and heating cycle of the regenerator,which is presumably the cause of excessive expansion and deformation of the volume of checker bricks.Therefore, improving the quality of bricks and reducing the impurity content are beneficial to prolonging the service life of the regenerator.