Hi, Roman, there are overnight soft sleeper train and D-prefaced trains available between Beijing and Shanghai. Say, D307 2130/0745 , the first class ticket is CNY542.00 net, while the second class is CNY452.00 net. For the soft sleeper, the lower berth is CNY499.00, CNY478.00 net for the upper berth. You can buy the train tickets from the railway station directly or the hotel you will stay in Beijing 10 days before. Since you will travel during the Spring Festival, the train tickets may hard to get. Good luck!