原因就是selinux
关闭selinux
selinux的配置文件在/etc/selinux/config，改成disable

或者给目录设置权限
chcon -R -t httpd_user_content_t public_html/
参考

http://www.toplee.com/blog/93.html

http://www.webjx.com/server/linux/server_linux_2007_11_05_525.html

http://www.libing.net.cn/read.php/957.htm