diff --git a/doc_related/preface.tex b/doc_related/preface.tex
index f8e0a05..bc58a7d 100644
--- a/doc_related/preface.tex
+++ b/doc_related/preface.tex
@@ -10,7 +10,7 @@
 {\Huge\textbf{山东第二医科大学指南}}\\[10pt]
 （简称：\colored{171}{79}{36}{321指南}）\\[30pt]
 %{\large\textbf{\colored{59}{100}{220}{3.0.7}}}\vspace*{-25pt}}
-{\large\colored{255}{0}{0}{319-Preview}}\vspace*{-25pt}}
+{\large\colored{255}{0}{0}{320-Preview}}\vspace*{-25pt}}
 \author{LinkChou\thanks{Compiled by \LaTeXe, CC BY-SA 4.0 LICENSE.\qquad%
         \uline{\href{Mailto:LinkChou@yandex.com}{Mailto: LinkChou@yandex.com}}\\
         \textbf{敬告：}\\