将下面代码复制粘贴到functions.php

/* 文章图片自动添加alt和title信息 */
function tin_image_alt($content){
global $post;
$pattern = "/<img(.*?)src=('|\")(.*?).(bmp|gif|jpeg|jpg|png)('|\")(.*?)>/i";
$replacement = '<img$1src=$2$3.$4$5 alt="'.$post->post_title.'" title="'.$post->post_title.'"$6>';
$content = preg_replace($pattern,$replacement,$content);
return $content;
}
add_filter('the_content','tin_image_alt',15);