The equipment,such as toiler,pressure vessel and pipeline,subjected to cyclical load suffer failure as a result of the low cycle fatigue (LCF).In this paper,based on the continuum damage mechanics(CDM)theory,the LCF damage variable is measured through stress amplitude method during the strain controlled tests,and a continuum damage model of isotropic LCF is derived.The material tested is a 10CrMo910 steel.The LCF damage evolution equation and life estimate have been derived by use of the effective stress concept and the hypothesis of strain equivalence.