\documentclass{beamer}
\definecolor{myblue}{RGB}{0, 100, 240}
\setbeamercolor{itemize item}{fg=myblue}
\setbeamercolor{itemize subitem}{fg=myblue}
\setbeamercolor{itemize subsubitem}{fg=myblue}
\setbeamerfont{itemize item}{size=\normalsize}
\setbeamerfont{itemize subitem}{size=\scriptsize}
\setbeamerfont{itemize subsubitem}{size=\tiny}
\defbeamertemplate*{itemize item}{mytheme}{%
\usebeamerfont*{itemize item}$>$
}
\defbeamertemplate*{itemize subitem}{mytheme}{%
\usebeamerfont*{itemize subitem}$>$
}
\defbeamertemplate*{itemize subsubitem}{mytheme}{%
\usebeamerfont*{itemize subsubitem}$>$
}
\begin{document}
\begin{frame}
\begin{itemize}
\item test
\begin{itemize}
\item test
\begin{itemize}
\item test
\end{itemize}
\end{itemize}
\end{itemize}
\end{frame}
\end{document}
![在此处输入图片描述](https://i.stack.imgur.com/8NHpM.png)