With the help of wjchen from http://forum.ubuntu.org.cn/viewtopic.php?f=42&t=372678,
and several try model options for my Realtek ALC262 device in corresponding section of http://www.kernel.org/doc/Documentat...dio-Models.txt
Finally, "fujitsu" works, although my laptop is Lenovo.
sudo vim /etc/modprobe.d/alsa-base.conf
add one line at the last
then the speakers of my laptop have sound when choose Analog Output in the Sound Settings.
options snd-hda-intel model=fujitsu
BTW, if I plug in 3.5mm socket with headphone, the Headphone will show in the Sound Settings, and it will sound when I choose it even if no change of alsa-base.conf. I didn't use my 3.5mm of my laptop before because this socket has some issues, only left channel sounds, so I usually use a external usb sound card MUSILAND US03 + Dual-RCA wire with my external HiVi speaker to listen in Windows. But unfortunately, alsa doesn't support MUSILAND card. so I can only depend on the speakers of the laptop itself