采用熔体抽拉法制备了直径59μm 的Co68.25Fe4.5Si12.25B15非晶丝，并在400℃、500℃进行了不同工艺的退火处理，分析了退火前后丝的巨磁阻抗（GMI）效应。结果表明，400℃退火处理降低了丝的各向异性场，提高GMI效应以及双峰出现频率，并大幅提高了磁场响应灵敏度。400℃保温20min退火样品双峰出现频率提高至13MHz。400℃保温80min退火样品低频GMI效应最强，最大阻抗变化率△Z/Z达到468.6%，5MHz时磁场响应灵敏度为57.9%/Oe。 500℃退火，由于晶化析出导致GMI效应降低，双峰出现频率降至3MHz。实验表明经适当退火处理的Co基熔体抽拉丝可用以制备高灵敏度磁传感器的磁敏材料。

Melt extraction Co68.25Fe4.5Si12.25B15 amorphous wires with diameter of 59μm were prepared and subjected conventional anneal at 400℃ and 500℃. The giant magneto impedance (GMI) effect of the as-cast and annealed wires were analyzed at low frequency (0.1MHz-13MHz). Actual results indicated that the anisotropy field was decreased when wires were annealed at 400℃, which induces the double-peak GMI appearance to a higher frequency. GMI effect and high field sensitivity were also improved after suitable anneal. The double-peak appearance increased to 13MHz of wires annealed at 400℃ holding for 20min. Wires holding for 80min at 400℃ showed best GMI effect. The largest impedance ratio △Z/Z was 468.6% and the field sensitivity went up to 57.9%/Oe at 5MHz. Crystalliztion reduced the magnetic softness and GMI response when anneal temperature increased to 500℃. These annealed melt extraction wires were ideally suitable for novel field GMI sensors applications after suitable anneal.