I think QT do support Chinese, maybe you need a unicode font which contains Chinese character.

I agree. We need several recipes to install some free Chinese fonts into Yocto Linux. I happened to port 2 font recipes from openembedded. Let me share them.

Please see http://git.yoctoproject.org/cgit/cgit.cgi/meta-intel-contrib/log/?h=esdc2012/poky
for the top 2 commits for the 2 font recipes.

Add the recipes into your poky source
code.

(If you have the git repository, this
should be very simple: $ git fetch
&& git rebase origin/esdc2012/poky)

Next, add a line into your local.conf
(please note: don't omit the space char before ttf-arphic-uming):

IMAGE_INSTALL_append
= " ttf-arphic-uming ttf-wqy-zenhei"

And use "bitbake core-image-sato" to generate a new .hddimg that will contain
the 2 fonts.

Or, just run "bitbake ttf-arphic-uming ttf-wqy-zenhei" and copy the generated
.rpm files(or .ipk depending the PACKAGE_CLASSES variable in your local.conf)
into your Yocto Linux that is already running and use "rpm -ivh
xxx.rpm" to install the packages. You may need to reboot to make the font
take effect.

BTW, the generated rpm files should be
inside tmp/deploy/rpm/all/, like

tmp/deploy/rpm/all/ttf-arphic-uming-20080216-r0.all.rpm

tmp/deploy/rpm/all/ttf-wqy-zenhei-0.6.26-r0.all.rpm

(If you use ipk, the files should be
inside tmp/deploy/ipk/all/. To install a .ipk package, use "opkg-cl
install xxx.ipk").