We need Chinese fonts. The fonts in Linux doesn't work. For example, pilfont.py can't convert the font file 'fangsongti24.pcf' located in my '/usr/share/fonts/bitmap-fonts/' directory. Fortunately we can use truetype fonts in Windows. Get a chinese font (I chose simsun.ttc) from Windows's 'windows/fonts' directory, and copy it to linux.
To draw Chinese text correctly into image file, use unicode. The following is an example:
#-*- coding:utf8 -*-
txt = '你好,世界!'
font = ImageFont.truetype('simsun.ttc',24)
im = Image.new("RGBA",(300,200),(0,0,0))
draw = ImageDraw.Draw(im)
#draw.text( (0,50), u'你好,世界!', font=font)
draw.text( (0,50), unicode(txt,'UTF-8'), font=font)