Where is the most professional badminton training in Beijing?
If you want to be a leader in the amateur circle, I recommend you to go to Shichahai Sports School ... which is a professional and systematic training.
If you play around by yourself, you can find a class somewhere and learn casually.
But I think you can learn the basic movements from the big class first, and then advise you to find a personal trainer to practice alone! It feels very useful!