Abstract: The column of 2 000 t hydraulic press ruptured when working. By means of macroscopic inspection,metallographic microanalysis and microscopic fracture analysis,the conclusions were drawn that the main reason caused the column rupture was some metallurgy defects inside the steel,and mechanical properties of the cog after heat-treatment could not meet request of the country standard,which caused early rupture along stress concentration area at root of beam′s step of the basement,by tensile stress and shearing stress functioning.