CoCr nanowire arrays with different compositions have been successfully synthesized in anodic aluminium oxide (AAO) template by alternating current (AC) electrodeposition. The effect of composition (Co and Cr) and annealing on magnetic properties and structural of nanowires were investigated. The results show that adding Cr to Co, coercivity (Hc) decreases from 1420 Oe (Co) to 1319 Oe (Co90Cr10). When the samples were annealed at 650 oC the Microstructure of nanowire was changed and also the coercivity was enhanced. By appropriate thermal annealing at 650 oC the coercivity of Co97.5Cr2.5 nanowires was improved from 1242 to 1790 Oe and the microstructure of nanowire was changed from hexagonal-close-packed (hcp) to face-centre-cubic (fcc). Morphology of template was studied by an atomic force microscope (AFM) and scanning electron microscope (SEM) was used to observe nanowires. The magnetic properties of samples were measured by alternative gradient force magnetic (AGFM) at room temperature. X-ray diffraction pattern has been used to determine crystalline structure of samples.