我突然想到：

echo \'<ul>\';
    the_random_posts();
echo \'</ul>\';

/**
 * Send random posts to the browser (STDOUT).
 */
function the_random_posts() {

    // Use your own category ids.
    $random_posts = array_merge(
        get_random_posts( 31, 3 ),
        get_random_posts( 11, 1 ),
        get_random_posts( 24, 1 )
    );

    foreach ( $random_posts as $post ) {
        // Change this line to code you want to output.
        printf( \'<li><a href="%s">%s</a></li>\', get_permalink( $post->ID ), get_the_title( $post->ID ) );
    }
}

/**
 * Get $post_count random posts from $category_id.
 *
 * @param int $post_count Number of random posts to retrieve.
 * @param int $category_id ID of the category.
 */
function get_random_posts( $category_id, $post_count ) {

    $posts = get_posts( array(
        \'posts_per_page\' => $post_count,
        \'orderby\'        => \'rand\',
        \'cat\'            => $category_id,
        \'post_status\'    => \'publish\',
    ) );

    return $posts;
}

如果任何帖子位于所选类别中的2个或多个类别中，则有可能会重复一篇帖子（如同时位于a类和B类中的帖子）。A.static variable 使用以前检索到的post数组可能会解决这个问题。

此算法按调用顺序打印帖子。

get_random_posts( 31, 3 ), // First, 3 random posts from Category A
get_random_posts( 11, 1 ), // Then,  1 random post  from Category B
get_random_posts( 24, 1 )  // Then,  1 random post  from Category C

如果你想要一个随机列表，shuffle $random_posts.