平均线膨胀系数的测定是材料热膨胀性能中的一个重要测试项目，在GB/T 1036-2008中规定了平均线膨胀系数通用的测试温度范围，但不同的温度范围会导致不同的测试结果，因此在实际应用中测试温度范围经常需要改变。试验选用4种环氧树脂，在不同的温度条件下对其平均线膨胀系数进行测定。结果表明：在较高温度范围下测试得到的环氧树脂平均线膨胀系数要大于较低温度范围下得到的结果，且在一定温度下材料可能会发生软化，影响线膨胀系数的测定结果。

The test of average coefficient of linear expansion is important in determining the thermal property of the materials. The general testing temperature range is specified in GB/T 1036-2008. But different temperature ranges would lead to different test results, thus the testing temperature range need to be changed usually in practical application. Four kinds of epoxy resins were chosen to test the average coefficient of linear expansion under different temperature condition. The results show that the average coefficient of linear expansion of epoxy resins obtained in higher temperature range was higher than that obtained in lower temperature range. Moreover, softening would happen to materials at a certain temperature, and influence the testing results of coefficient of linear expansion.