μ 子是地球表面可以探测到的主要宇宙射线，是标准模型中一种重要的基本粒子.μ 子衰变产生电子和中微子.通过 μ 子寿命的测量不仅可以加深学生对μ 子衰变性质的理解，还可以加深对狭义相对论时间膨胀效应的认识.本文通过NaI (Tl) 闪烁体探测器捕捉宇宙射线μ 子及其衰变电子信号，介绍了一种在实验室中测量μ 子平均寿命的简易实验方法.

The muon is the main part of cosmic rays which can be detected on the Earth’s surface and an elementary particle of standard model. The muon decays to an electron and neutrinos. The lifetime measurement of muon can help students to know the decay properties of muon and also the time dilation effect of special relativity. In this paper，a NaI( Tl) detector is used to detect the signals of stopped muon and its decay electron. A simplified experimental method is introduced to measure the mean lifetime of muon in the laboratory