How can i go to Xian North railway station from Xianyang airport

Firstly, no direct shuttle bus can take you there.
Here is my suggestion:
You can take shuttle bus line 4 to Xiaozhai Station. After that, you can take subway line 2 to the North Railway Station directly.
Or you can take a cab to the train sttaion in about 20 min, spending about 50-60 RMB.