i want to vist, bejing-dandong-shanghai-taizhou-tai'an-bejing give me train and by air option

Pek to Dandong and Dandong to Shanghai, I suggest you take the direct flight to your destinations 'cause the train takes too much time.
Shanghai to Taizhou, you can choose the train. And the whole journey takes about 4.5 h.
Taizhou to Taian, only one train is in service between the two places. So you can go to Luqiao Bus Station to take the direct bus to Taina.
Tainan to Pek, the bullet train is suggested. You only need about 2-3 h for the whole journey.
By the way, for convenience, I suggest you book the ticket in advance and the following website may help you a lot:
https://www.travelchinaguide.com/china-trains/