Currently, there is no direct flight or train between Yiwu and Xian. So, please transfer at Shanghai or Hangzhou. Firstly, you could take a train from Yiwu to Shanghai or Hangzhou quickly. And then, you could fly to Xian in 2 hours or take a train to Xian. The train and flight info could be search respectively at: China Flight(https://www.travelchinaguide.com/china-flights/) and China Train(https://www.travelchinaguide.com/china-trains/) .