To travel by train from Paris in France to London in the United Kingdom, you have to cross the Channel.
The fastest option is by direct Eurostar train from Paris or Lille to London. If you want to save money, think about using a bus.
1 巴黎 (法国) - 伦敦 (英国)
To travel from Paris to London by train, you have to use the direct Eurostar train. The journey time is about 2:30 h.
Buy your train ticket for Eurostar and find schedules via the given booking links. As earlier you book, as cheaper the ticket prices are.
An other travel option is to use a bus. The journey is much longer, but usually cheaper. Flixbus runs this route several times per day (also over-night), but as well other bus companies.
The journey by train and including the ferry Calais (France) to Dover (United Kingdom) is for now no nice option anymore. The journey is long and the ferry got really expensive for foot passengers since several years.
Eurail: 如果如果在这条路线上您想使用Eurail而不是火车票, 请您查看这里，关于预订费及其他信息。