利用热膨胀仪测量了铍材的平均线膨胀系数，分析了影响铍材平均线膨胀系数测量不确定度的因素，并对铍材平均线膨胀系数测量不确定度进行了评定。结果表明：影响平均线膨胀系数测量不确定度的因素主要有测量重复性、热膨胀分析仪测量精度、初始长度L₀测量及数值修约。在（12.01-0.21）×10^-6 ℃^-1至（12.01+0.21）×10^-6 ℃^-1的区间包含了平均线膨胀系数测量结果可能值的95%，即在95%置信度下平均线膨胀系数的扩展不确定度为0.21×10^-6 ℃^-1。

The average linear expansion coefficient of beryllium material was measured by thermal dilatometer. The factors of uncertainty affecting the measurement of average linear expansion coefficient of beryllium material were analyzed, and the measurement uncertainty of average linear expansion coefficient of beryllium material was evaluated. The results show that the main factors that affect the measurement uncertainty of average linear expansion coefficient the measurement repeatability, the measurement accuracy of thermal expansion analyzer, the measurement of initial length L₀ and the rounding off of values. In the range of (12.01-0.21)×10^-6 ℃^-1 to (12.01+0.21)×10^-6 ℃^-1 contains 95% of the possible value of average linear expansion coefficient, that is, the expanded uncertainty of average linear expansion coefficient is 0.21×10^-6 ℃^-1 under the 95% confidence level.