One Piece in China

Taiwanese Dub
The Taiwan Dub of One Piece (called "航海王" or "sea king" in english) began to air on TVB in China around 2000. The dub is uncensored and the openings are left in Japanese. A new epsiode currently airs every week on TTV and is usually very close to the Japanese version (usually 20 or so epsiodes away from the current Japanese epsiode). All of the movies (except Stong World) have been dubbed in Taiwanese as well.

Here's TTV's website for One Piece

Cantonese Dub
The Cantonese Dub aired in mainland China sometime in 2000-2001. Little is known about this dub in the english community.