三级标题的设置问题

\renewcommand{\contentsname}{\centerline{\heiti\zihao{4}目\quad 录}}
\titlecontents{section}[0pt]{\vspace{.25\baselineskip}\fangsong\zihao{-4}} {\thecontentslabel\quad}{} {\hspace{.5em}\titlerule*[5pt]{$\cdot$}\contentspage}
\titlecontents{subsection}[0pt]{\vspace{.25\baselineskip}\fangsong\zihao{-4}} {\thecontentslabel\quad}{} {\hspace{.5em}\titlerule*[5pt]{$\cdot$}\contentspage}
\titlecontents{subsubsection}[0pt]{\vspace{.25\baselineskip}\fangsong\zihao{-4}} {\thecontentslabel\quad}{} {\hspace{.5em}\titlerule*[5pt]{$\cdot$}\contentspage}
\renewcommand{\theequation}{\arabic{section}.\arabic{equation}}%让公式与章节相关联
\usepackage{titlesec}%标题
\titleformat{\section}[hang]{\raggedright\zihao{4}\fangsong}{\thesection}{1em}{}{}
\titlespacing{\section}{0pt}{4pt}{4pt}
\titleformat{\subsection}[hang]{\raggedright\zihao{-4}\heiti}{\thesubsection}{1em}{}{}
\titlespacing{\subsection}{0pt}{0pt}{0pt}
\titleformat{\subsubsection}[hang]{\zihao{-4}\fangsong}{\thesubsubsection}{1em}{}{}
\titlespacing{\subsubsection}{0pt}{0pt}{0pt}
但是就不知道三级标题怎么设置。