Former WWE superstar Chyna is finally getting back in the ring ... taking on 9 dudes at the same time ... except it's for a porno movie.

TMZ has learned ... Chyna was totally serious about pursuing a XXX career ... and just wrapped up on a Royal Rumble-inspired flick in which she locks up with a bunch of dudes who all look like famous wrestlers ... including a wannabe Hulk Hogan, wannabe Triple H, wannabe Ric Flair and more.

Weird thing is ... Chyna and the REAL Triple H actually dated for a while before he married Stephanie McMahon back in 2003.