\documentclass{book}
\usepackage[top=30mm, bottom=30mm, left=30mm, right=40mm]{geometry}
\usepackage{xepersian}
\makeatletter
\renewcommand\tableofcontents{%
    \if@twocolumn
      \@restonecoltrue\onecolumn
    \else
      \@restonecolfalse
    \fi
    {\centering\interlinepenalty\@M%
    \Huge\bfseries\parindent \z@%
    \vspace*{3\baselineskip}\contentsname\thispagestyle{plain}
        \@mkboth{%
           \MakeUppercase\contentsname}{\MakeUppercase\contentsname}\par\nobreak}%
    \par\vspace{2\baselineskip}
    \@starttoc{toc}%
    \if@restonecol\twocolumn\fi
    }
\makeatother
\begin{document}
\tableofcontents
\chapter{فصل اول}
\section{بخش اول}
مقداری متن ...
\end{document}