I want to travel from Beijing to Changde to Wenzhou and SHenzhen and then to Hongkong. Please advice

You can fly from Beijing to Changde directly!

From Changde to Wenzhou, there are direct long-distance buses in service. I remember they leave Chengde General Bus Station at 11:45 and 12:30.

For the third trip, do you refer to travel from Wenzhou to Shenzhen? If so, you can take buttle train from Wenzhou South to Shenzhen North!

From Shenzhen to Hong Kong, you can go to Luohu to cross the border to Lo Wu in Hong Kong. Then take local East Rail line to the downtown!