diff --git a/sjtuthesis.cls b/sjtuthesis.cls
index dbd8dc95..f718371f 100644
--- a/sjtuthesis.cls
+++ b/sjtuthesis.cls
@@ -72,6 +72,7 @@
 \RequirePackage{pdfpages}
 \RequirePackage{calc}
 \RequirePackage{algorithm, algorithmic}
+\RequirePackage{siunitx}
 
 %==========
 % Segment 2. Define general-purpose LaTeX commands.
diff --git a/tex/example.tex b/tex/example.tex
index 4044da6f..41f5aee0 100644
--- a/tex/example.tex
+++ b/tex/example.tex
@@ -79,6 +79,10 @@ \subsection{公式排版}
       \nabla _{k}R_{ij}\right ]\vphantom {\sum _{i<j}}\right )
 \end{multline}
 
+\subsection{SI单位}
+
+使用\verb+siunitx+宏包可以方便地输入SI单位制单位，例如\verb+\SI{5}{\um}+可以得到\SI{5}{\um}。
+
 \subsubsection{一个四级标题}
 \label{sec:depth4}