function generateTree($items){
    $tree = array();
    foreach($items as $item){
    if(isset($items[$item['pid']])){
    $items[$item['pid']]['son'][] = &$items[$item['id']];
    }else{
    $tree[] = &$items[$item['id']];
    }
    }
    return $tree;
    }
    $items = array(
    1 => array('id' => 1, 'pid' => 0, 'name' => '安徽省'),
    2 => array('id' => 2, 'pid' => 0, 'name' => '浙江省'),
    3 => array('id' => 3, 'pid' => 1, 'name' => '合肥市'),
    4 => array('id' => 4, 'pid' => 3, 'name' => '长丰县'),
    5 => array('id' => 5, 'pid' => 1, 'name' => '安庆市'),
    );
    print_r(generateTree($items));