To improve the sensing characteristics of a Fiber Bragg grating(FBG) temperature sensor with a Ni coating , the causes of the hysteresis error and the difference of sensitivities when it was heated and cooled were researched. Results indicate that the residual stress induced by electroless-e-lectroplating makes the sensor imprecise. The mechanism of the residual stress was discussed * then a heat treatment method was proposed for the metallized FBG(MFBG) with a nickel coating. In treatment, the MFBG sensor was put in a drying oven at 120 °C for 8 hours three times,and every time it was cooled with the oven. A comparison experiment for the MFBG with the nickel coating was performed in 100 - 300 ℃ ,results show that the hysteresis error of the sensor is 6. 64%, and the differ-ence of sensitivities when it is heated and cooled is more significant before the heat treatment. The sensor characteristics are not be amended even if it is performed temperature cycle again after half a month. However, the hysteresis error of the sensor is descended to 3. 62%, and the sensitivities of the MFBG when it is heated and cooled are 22. 84 pm/℃ and 22. 76 pm/℃ respectively, after the heat treatment. The experiments demonstrate that with a higher sensing accuracy, the working range of the MFBG with the nickel coating has expanded to 300℃ after effective heat treatment.%为了改善镍保护后光纤布拉格光栅(FBG)的高温传感性能,即降低其回程误差,减少其升温与降温灵敏度的差异,本文研究了产生这些现象的原因,认为其主要源于化学镀结合电镀镍过程中的残余应力.讨论了残余应力产生的机理,提出了适用于镍金属保护FBG的热处理方法.三次将金属镍保护后的FBG放置在120℃恒温炉中保温8h后随炉冷却,对热处理前后的镍保护布拉格光纤光栅进行100～300℃的循环温度传感对照实验.结果显示:热处理前回程误差为6.64％,升温与降温灵敏度有较显著差异,且放置半个月后再次进行传感实验其特性也没有改善；热处理后,回程误差降到3.62％,升温灵敏度为22.84 pm/℃,降温灵敏度为22.76 pm/℃.实验表明,经适当热处理后的镍保护布拉格光纤光栅的实际工作温度可扩展到300℃,且具有较高的传感精度.
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