If you mean your kde is english that mean you haven't set the kde, you should install the kde language package and set the font in the control ,and be sure you have install the chinest font.
I always use kde in English,and sure I have Chinese fonts installed.my web browser and kwrite works well with chinese contents.
and i always use "startx" to enter kde.
manually run command : export LANG="en_US.UTF-8"
export LC_CTYPE="zh_CN.UTF-8"
LANG=en_US.UTF-8
LC_CTYPE=zh_CN.UTF-8
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=
but still , it doen't has any actual effect .....