In order to improve the giant magneto impedance (GMI) of Co-rich wires for high sensitive sensor applications,Co68Fe4.5Si15B12.5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile stresses applied.And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz.It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments,because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy,which improved the circular permeability and GMI effect.Their impedance ratio AZ/Z increased from 244％ to 480.9％ at 7 MHz and the field sensitivity increased to 0.83％/(A/m) at 5 MHz,when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min.It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.