There are direct flights from xian to Jiuzhaigou in high seasons. You may check the cost and duration time at China Flights(https://www.travelchinaguide.com/china-flights/) by entering the departure and arrival stations.

No direct train frm xian to Jiuzhaigou, you need to go to Chengdu first(about 16 hours;the hard seat is about rmb115, the hard sleeper is about rmb200, soft sleeper is about rmb300)

hello mr chang,
i think there is a slight error in your reply.
you've replied mr patrick ang in my post.

Oh, very sorry for that. Usually it begins to snow in mid november in jiuzhaigou. For travel agencies, I think you may contact this web:www.travelchinaguide.com, I know they offer tailor-made tours based on tourists' preference.