In order to improve the problem of insufficient measurement scale and accuracy in the process of fracture toughness testing by indentation method， a method for assessing the fracture toughness of steel based on Berkovich indentation strain energy density （SED） is proposed based on the critical indentation energy （CIE） method. The fracture toughness of nine steels is evaluated by considering both elastic and plastic energies and correcting the critical total pressure depth. The results show that the relative error of the toughness measured by considering only the plastic energy is found to be in the range of 5% to 20%， whereas the relative error of the toughness measured by considering both the elastic and plastic energies is found to be within 5%. At the same time， determining the fitting range for the critical total indentation depth requires avoiding the region where the elastic modulus of the material rises near the surface. These improve the accuracy of evaluating the fracture toughness of steel based on the CIE method using the Berkovich indenter.