文章讨论了动态有效位数的含义及溯源性 ,介绍了评价动态有效位数的两种方法———正弦波拟合法和FFT法 ,并讨论了各自的优缺点。另外 ,详细讨论了评价动态有效位数过程中应注意的几个问题 :等相位密度采样问题、整周期信号采样问题、拟合收敛性问题、拟合初始值选取问题和校准软件评价问题等。同时给出了两条具有典型代表性的动态有效位数频率特性曲线的实测例证 This paper discusses the meaning and traceability of the number of dynamic significant digits, introduces two methods of evaluating the number of dynamic significant digits - the sine wave fitting method and the FFT method, and discusses their respective advantages and disadvantages. In addition, several issues that should be paid attention to in the process of evaluating the dynamic significant digits are discussed in detail: equal phase density sampling, whole periodic signal sampling, fitting convergence, fitting initial value selection and calibration software evaluation. At the same time, two typical examples of the dynamic characteristic of the frequency of the median frequency characteristic curve are given