I would like to know what ways there are to go from xian to Jiuzhaigou

Here are the ways for your choices:
1. There are direct planes between, and you can fly to Huanglong Airport ina round 1 hour and 5min. Upon arrival there, you can take a shuttle bus to JZG.
2. Take a train from Xian to Chengdu. At Chengdu Xinnanmen Bus Station, there are buses to JZG.