visa status

Sorry but if you leave Germany to work in China for such a time period you will lose your residency after 6 months anyway and have to start over again if you return afterwards. And your time to get citizenship will also start at zero upon returning. And no, you cannot naturalize as German from abroad. You will have to stay in Germany for a minimum of 3 continuous years (non-EU people not married to a German need 8 years) and pass the citizenship and B1 German exams as well as have a reliable income so that you don’t need public assistance. Plus they check that one has no criminal record or association with undemocratic or terrorist organizations and has paid their taxes and social contributions.

But this subject has been covered many time on this site. You should familiarize yourself with the German Immigration Authority (Bamf) Website for details. I am giving a link to the English version page concerning non-EU citizen immigrants.

https://www.bamf.de/EN/Themen/Migration … -node.html

Thank you Tom.
I'm grateful that you reply my queries.
I have to move to China only because of my husband's work transfer and he is German.
In any case,Is it compulsory that I have to stay and work in Germany to apply for citizenship ?
What if someone is a housewife and have no personal income, she can't apply for German citizenship? like never ?  it will be kind if you share your knowledge about this with me . Thank you again 

You do not have to work, but you have to live in Germany without needing public financial assistance to become citizen. There are of course many other rules and requirements to become German - you should read about those!