transportation from ZhangJiaJe to chengdu

Well, you can take a train from Zhangjiajie to Huaihua first. Then transfer a train to get to Chengdu East Railway Station.
Generally speaking, you can spend two days in Zhangjiajie and two/three days in Chengdu downtown.
In Zhangjiajie, first of all, the must see is Zhangjiajie Scenic Spot. In addition, Wulingyuan Scenic Area and Tianzi Mountain Nature Reserve are also good choices.

In Chengdu, you can go to Chengdu Research Base of Giant Panda Breeding,Chunxi Road and Jinli Street. All of these scenic spots win high popularity among tourists. THe surroundin sites like Leshan Giant Buddha and Mt. Emei are worth visiting too. If you have more time, Jiuzhaigou is also a nice destination.

Have a good journey!