MarkMas is correct.
Fastest train is the Maglev in Japan, at 375mph...
Well, I seem to have been awarded the prize for saying "Japan (maybe China)" which seems like a pretty feeble response, but onward, I guess!
I've now looked it up and it seems like the
Shanghai Maglev Train (in China, not Japan, then) is the fastest commercial service at 431 km/h (268 mph), and the fastest conventional train is the Chinese CR400 running on the Beijing–Shanghai line which can run at 350, but this seems debatable as it actually runs at 300 km/h, and there are several trains in France, Germany, Spain and Japan that regularly run at 320. Meanwhile, yes, there was a speed record run by a
Maglev train in Japan, which hit 375mph - but I'd never heard of that until just now!