QUOTE(xliu5 @ Jun 16 2006, 12:45)

Chinese coded in GBK (…APE tags)
…No.
QUOTE(xliu5 @ Jun 16 2006, 12:45)

I guess that ID3v1 does not support unicode encoding
Correct.
QUOTE(xliu5 @ Jun 16 2006, 12:45)

the MP3 player most certainly does not read APE tags
That would be likely.
QUOTE(xliu5 @ Jun 16 2006, 12:45)

even if I converted files codepage to unicode encoding.
And that has nothing to do with the APE tag itself, unless you had some misread ANSI characters. In either case, the APE tag would be UTF-8.
QUOTE(xliu5 @ Jun 16 2006, 12:45)

So the only option to let the MP3 player showing Chinese is to add ID3v2.3 UTF-16 tag, in addition to the other two tags I have already had since foobar2k 0.83.
Pity you can't do that. Maybe bug your player manufacturer for a firmware update? (Yeah, fat chance of that happening, I suppose.)
Is it supported by Rockbox?