When I was a child, my family was poor and I sent my brother away for more than 20 years. I only know that he is in Hangzhou. How can I find him?

You can send it to search for you. Now the network is quite developed. If your brother has a birthmark, try to write it clearly. It's best to ask who it was given to, the physical characteristics of that person and so on. It is easy to find the younger brother. If you still find it difficult, you can seek the help of the media. I believe this is no problem.