book第一章有附录，结果后续章节都是附录的样式，怎么改过来？

可以使用

\usepackage{appendix}
\renewcommand{\setthesection}{附录\thechapter.\arabic{section}}
\renewcommand{\setthesubsection}{附录\thesection.\arab{subsection}}

替代

\renewcommand\appendix{\par
\setcounter{section}{0}
\setcounter{subsection}{0}
\gdef\thesection{附录 \Alph{section}}}

然后把chp03.tex和chp02.tex中的appendix改成subappendices,还有注释掉\appendix,他会给后面的全部变成附录内容,然后编译就行了,我这里的结果是这样的

1. 在 ch03.tex 开头加上 \appendix
2. 将 \appendix 改为

\renewcommand\appendix{\par
    \setcounter{section}{0}
    \setcounter{subsection}{0}
    \gdef\thesection{附录 \Alph{section}}
    \ctexset{
        section/tocline = 附录 \thechapter.\arabic{##1} ##2
    }%
    }

这样的用法就比较奇怪了，最好使用 appendix 宏包来实现，看看这里：https://tex.stackexchange.com/questions/120716/appendix-after-each-chapter

\documentclass{book}
\usepackage{appendix}
\usepackage{chngcntr}
\usepackage{etoolbox}
\usepackage{lipsum}

\AtBeginEnvironment{subappendices}{%
\chapter*{Appendix}
\addcontentsline{toc}{chapter}{Appendices}
\counterwithin{figure}{section}
\counterwithin{table}{section}
}

\begin{document}

\tableofcontents
\chapter{Test Chapter One}
\section{A regular section}
\section{Another regular section}
\begin{subappendices}
\section{Some title for an appendix}
\lipsum[4]
\section{Some title for an appendix}
\lipsum[4]
\end{subappendices}
\chapter{Test Chapter Two}
\section{A regular section}
\section{Another regular section}
\begin{subappendices}
\section{Some title for an appendix}
\lipsum[4]
\section{Some title for an appendix}
\lipsum[4]
\section{Some title for an appendix}
\lipsum[4]
\end{subappendices}

\end{document}