从试验方法上对塑性应变比r值的测量不确定度进行了评定，并对试样尺寸测量和引伸计等方面引起不确定的因素进行了讨论和计算。在评定合成不确定度时，应根据塑性应变比r值的计算公式计算各不确定度分量的灵敏系数;当输入量明显相关时，计算公式中应考虑相关系数的作用。

The testing methods was used to evaluate measurement uncertainty of plasticity stress ratio r values,the uncertainty factors such as specimen dimension measurement and extensometer were discussed and calculated. It was indicated that,when the combined uncertainty was evaluated,the sensitivity coefficient of each uncertainly weight variables should be calculated by plastic stress ratio r value equation;when the input quantities were apparent correlative,the effect of correlation coefficient should be take into account in equation.