Abstract: The sensitivity of HQ80C steel to the reheat cracking was investigated by using the equi-temperature implant test,the Tekken test and the high-temperature tensile test.The conditions causing the reheat cracking were discussed utilizing the strain concept.Moreover,a scheme was proposed,which porfeotly discribes the relationship among the fectors affecting the reheat cracking.In this paper,the authors suggest a new oriterion of the reheat cracking——(ε_r) min,and desoribe its reasonableness and advantages.The less (ε_r) min is,the higher is the sensi-tivity of the materials to reheat cracking.