通过使用comment_form( $args, $post_id ) 您可以像这样在评论表单中添加额外字段

$commenter = wp_get_current_commenter();
$req = get_option( \'require_name_email\' );
$aria_req = ( $req ? " aria-required=\'true\'" : \'\' );
$fields =  array(
    \'author\' => \'<p class="comment-form-author">\' . \'<label for="author">\' . __( \'Name\' ) . \'</label> \' . ( $req ? \'<span class="required">*</span>\' : \'\' ) .
        \'<input id="author" name="author" type="text" value="\' . esc_attr( $commenter[\'comment_author\'] ) . \'" size="30"\' . $aria_req . \' /></p>\',
    \'email\'  => \'<p class="comment-form-email"><label for="email">\' . __( \'Email\' ) . \'</label> \' . ( $req ? \'<span class="required">*</span>\' : \'\' ) .
        \'<input id="email" name="email" type="text" value="\' . esc_attr(  $commenter[\'comment_author_email\'] ) . \'" size="30"\' . $aria_req . \' /></p>\',
);

$comments_args = array(
    \'fields\' =>  $fields
);


comment_form($comments_args);

还有Customizing Comments 字段

我们甚至可以使用“comment\\u form\\u default\\u fields”过滤器向注释中添加字段。将此添加到函数中。我们可以添加如下字段：

function add_comment_fields($fields) {

$fields[\'age\'] = \'<p class="comment-form-age"><label for="age">\' . __( \'Age\' ) . \'</label>\' .
    \'<input id="age" name="age" type="text" size="30" /></p>\';
return $fields;
}

add\\u filter（\'comment\\u form\\u default\\u fields\'，\'add\\u comment\\u fields\'）；

#respond .comment-form-author label,
#respond .comment-form-email label,
#respond .comment-form-url label,
#respond .comment-form-age label,
#respond .comment-form-comment label {
background: #eee;
-webkit-box-shadow: 1px 2px 2px rgba(204,204,204,0.8);
-moz-box-shadow: 1px 2px 2px rgba(204,204,204,0.8);
box-shadow: 1px 2px 2px rgba(204,204,204,0.8);
color: #555;
display: inline-block;
font-size: 13px;
left: 4px;
min-width: 60px;
padding: 4px 10px;
position: relative;
top: 40px;
z-index: 1;
}

Reference url