Is it possible to go by bus to both Jiuzhaigou and Huanglong in the same trip from Chengdu,

You can take a bus from New South Gate Bus Station to Jiuzhaigou, the departure time is 8:00 - 8:20.The fare is about CNY 150 and it takes about 8 to 9 hours to get there and you can just enter the scenic area the second day. From Jiuzhaigou to Huanglong, you need to take a bus in Jiuzhaigou County, the Jiutong Bus Station. The bus departs from 6:30-7:30. The fare is CNY 40 and it takes 2 to 3 hours.

In addition, you need to order the tickets in advance in both stations.