第一，找到主题文件夹

第二，复制下面代码放入 AutoNumber.css文件中

body {
  counter-reset: h1;
}


#write h1,
.markdown-section h1 {
    counter-reset: h2;
}

#write h2,
.markdown-section h2 {
    counter-reset: h3;
}

#write h3,
.markdown-section h3 {
    counter-reset: h4;
}

#write h4,
.markdown-section h4 {
    counter-reset: h5;
}

#write h5,
.markdown-section h5 {
    counter-reset: h6;
}

#write h1::before,
.markdown-section h1::before {
    counter-increment: h1;
    content: counter(h1) ". ";
}

#write h2::before,
.markdown-section h2::before {
    counter-increment: h2;
    content: counter(h1) ". "counter(h2) " ";
}

#write h3::before,
.markdown-section h3::before {
    counter-increment: h3;
    content: counter(h1) ". "counter(h2) "."counter(h3) " ";
}

#write h4::before,
.markdown-section h4::before {
    counter-increment: h4;
    content: counter(h1) ". "counter(h2) "."counter(h3) "."counter(h4) " ";
}

#write h5::before,
.markdown-section h5::before {
    counter-increment: h5;
    content: counter(h1) ". "counter(h2) "."counter(h3) "."counter(h4)"."counter(h5) " ";
}

#write h6::before,
.markdown-section h6::before {
    counter-increment: h6;
    content: none;
}

如图

第三，在当前使用主题css文件中 顶部 引入该文件@import "AutoNumber.css";

第四，从新打开Typora