Well, I've just retreived the answer from the Arch Forum. It's just because the missing of dependency of libsndfile 2008/8/17 Christian Leng <rookie999.ly@gmail.com>:

Hi, I'm a new user of Arch. I've installed openoffice via pacman. However, it doesn't work anyway. Accoring to the Arch Wiki, I added 'OOO_FORCE_DESKTOP=gnome' into my ~/.bashrc, but nothing changed. Clicking at the OOo items in the desktop menu, nothing happens. Then when I tried to run OOo from the terminal using command "$/usr/bin/soffice", error info is: ------------------- no suitable windowing system found, exiting. -------------------

I just don't know what is the matter.