Damage and fracture processes of concrete are attended with energe dissipation or nonreversible thermodynamics process.Essence of damage and fracture is a interlaced coupling process.In view of I-type crack and beased on dual G model theory and damage energy release rate concept

this paper deduces coupling parameters between damage field and fracture field for tip region of crack

i.e.damage type′s energy release rate.The virtual crack closure technique（VCCT） was used for numerical simulation of a set of three-point bending beam.Results show that this parameter can be used to discribe the physical field in crack neighborbood instead of concept of energy release rate in non-loss material.Comparing it with the regulation regarding change of energy release rate G and damage energy release rate Y with crack length

the damage-type energy release rate corresponding to instability of crack was presented and it is explained that damage-type energy release rate can describe coupling field of damage fracture in tip region of crack reasonably.