您可以检查主循环中的迭代$wp_query->current_post

while( have_posts() ){
    the_post();

    the_title();

    // count starts at zero, so after 1 will be after 2nd post
    if( 1 == $wp_query->current_post ){
        the_widget( \'WP_Widget_Recent_Posts\' );
    }

}

ob_start();
the_widget( \'WP_Widget_Recent_Posts\' );
$widget_output = ob_get_clean();