I want to be a graduate student in China. What major is better for immigrants to study abroad?

It depends on whether you want to invest in immigration or skilled immigration and which country you immigrate to.

Basically, immigrant countries usually consider the conditions of skilled immigrants: education, age and job. If you have a degree, there are enough graduate students, and it is enough to graduate from a foreign local degree. As long as you are not too old, say, over 50, it's not a big problem. Work experience is not too much, so it doesn't need to be considered. The problem is that you have to find a job in your field. The employer who works is willing to give you an employment contract, so basically there is no problem with immigration. I know countries like Canada, New Zealand and Australia. As for Britain, France and Germany, it is more troublesome. You need to study or live in that country for a certain number of years before you can apply. The details are not clear.