We have demonstrated that the bulk-like contribution to tunnelling magnetoresistance(TMR) exists in the magnetic tunnel junctions,and is determined by the tunnelling characteristic length of the ferromagnetic electrodes.In the experiment,a wedge-shaped CoFe layer is inserted at the interface between the insulating barrier and the reference electrode.It is found that TMR ratio increases from 18% without CoFe layer to a saturation value of 26.5% when the CoFe thickness is about 2.3 nm.The tunnelling characteristic length,ltc,can be obtained to be about 0.8 nm for CoFe materials.