Applying for a J.D in US does not require you having a legal background. As long as you are keen on studing American law, you may give it your best shot. Besides,you might have some kinda avantage in LSAT due in large part that you have beening working for MS where the official working language is English. It is worth noting that tuition for J.D. programme is kinda unaffordable for an ordinary Chinese applicant.