利用宇宙射线进行探测器模型的性能测试是高能物理普遍采用的方法,其中最重要的步骤之一就是确定宇宙线入射的准确位置和径迹．多数采用丝室探测器来进行宇宙线的精确定位,需要很高的造价和复杂的电子学系统．本文介绍一种简单的定位方法,采用塑料闪烁体条加波移剂光纤编码读出的方式,可以实现精度为1cm的定位．据此建立了一套实验装置,对BESⅢ电磁量能器CsI(T1)晶体探测器单元的光输出强度和不均匀性进行了测量． Performance testing of detector models using cosmic rays is a commonly used method of high-energy physics. One of the most important steps is to determine the exact location and track of cosmic ray incidence. The majority of satellites used for precise positioning of cosmic rays require high cost and complex electronics systems. This article describes a simple positioning method, the use of plastic scintillator plus wave coder fiber encoding read out, you can achieve the accuracy of 1cm positioning. Based on this, an experimental set-up was set up to measure the light output intensity and inhomogeneity of CsI (Tl) crystal detector unit of BESIII electromagnetic calorimeter.