How can Nanjing recruit extras?

Not in Nanjing. Actors don't recruit, they only coordinate from the inner circle, and there is no external recruitment. Who says they are recruiting actors is equivalent to who declares himself a liar! If you are a man, there are only two places in the country where you can be an extra, namely, Hengdian Film and Television City in Zhejiang or the gate of Beijing Film Studio. There is no other way. If you are a woman. I don't advise you to go, it's not safe there.