A simple Tsinghua letterhead template.
\documentclass[12pt]{article}
\usepackage[utf8x]{inputenc}
\usepackage[BoldFont,SlantFont]{xeCJK}
\usepackage[left=3cm,right=3cm,top=5cm,bottom=3cm,footskip=2cm,headheight=4cm,headsep=1cm]{geometry}
\usepackage{graphicx}
\usepackage{fancyhdr}
\usepackage[export]{adjustbox}
\usepackage{tabularx}
\usepackage[hidelinks]{hyperref}
\usepackage{lipsum}
% \setCJKmainfont[BoldFont = simhei.ttf]{simfang.ttf}
% \defaultfontfeatures{Scale=1.2}
% \linespread{1.2}
\usepackage{zhnumber}
\fancypagestyle{plain}
{\fancyhf{}
\fancyhead[L]{\includegraphics[height=3.2cm]{logo.png}}
% \fancyhead[R]{\Large 清华大学\phantom{a} \\ 数学科学系}
\fancyhead[R]{\large Tsinghua University \\ Department of Mathematical Sciences}
\renewcommand{\footrulewidth}{.4pt}
\fancyfoot[L]{
\resizebox{!}{3\baselineskip}{\begin{tabular}[b]{@{} l @{}}
Prof. Dr. xxx \textbf{xxx} \\
Professor in Mathematics - Tsinghua University \\
Beijing 100084, China \\
Fax: xxxxxxxxxxxxxxxxxxxx \\
Email: \href{mailto:xxx@math.tsinghua.edu.cn}{\nolinkurl{hzhang@math.tsinghua.edu.cn}}
\end{tabular}}}
}
% \fancypagestyle{myfancy}
% {\fancyhf{}
% \fancyhead[L]{\includegraphics[height=3.6cm]{logo.png}}
% % \fancyhead[R]{\Large 清华大学\phantom{a} \\ 数学科学系}
% \fancyhead[R]{\large Tsinghua University \\ Department of Mathematical Sciences}
% \renewcommand{\footrulewidth}{.4pt}
% \fancyfoot[L]{
% \resizebox{!}{3\baselineskip}{\begin{tabular}[b]{@{} l @{}}
% Prof. Dr. Hechun \textbf{Zhang} \\
% Professor in Mathematics - Tsinghua University \\
% Beijing 100084, China \\
% Fax: +86(10)62781785 \\
% Email: \href{mailto:hzhang@math.tsinghua.edu.cn}{\nolinkurl{hzhang@math.tsinghua.edu.cn}}
% \end{tabular}}}
% }
\pagestyle{plain}
\pagenumbering{gobble} % switch off page numbering
\begin{document}
% Date: \zhtoday
% Time: \zhcurrtime
% \zhnumsetup{time=Chinese}
% Date: \zhtoday
% Time: \zhcurrtime
% \zhnumsetup{time=Arabic}
% 1586/08/17: \zhdate{1586/08/17}
% \begin{letter}{}
% \
% \vspace{2.7cm}
{\Large \noindent 尊敬的XXX：}
\vspace{1em}
\large
\setlength\parindent{2em}
\lipsum
\vspace{2em}
此致
\noindent 敬礼
\vspace{2em}
\begin{flushright}
XXX
\zhtoday
\end{flushright}
% \end{letter}
\end{document}