Have you tried getting your wife US citizenship? I have dual citizenship with US & UK. It took me about 9 months to get. I wasn't going to go for it as I was worried about losing my UK citizenship but after 9/11 (I needed to secure all our finances for our children if anything happened to my husband) I looked into it more and found that I didn't have to lose my UK citizenship. It was just a thought, as your wife could then apply for a visa as a US citizen instead. I don't know the legalities for Chinese dual citizenship... but just a thought.