back office       
noun [ C usually singular ] uk/ˌbæk ˈɒf.ɪs/ us/ˌbæk ˈɑː.fɪs/
 (公司的)事务部门,后勤部门
the part of a business company that is concerned with running the company and that does not deal directly with customers or the public 
  I worked for several years as an administrator in the back office of a large corporation. 我曾在一家大型公司的事务部门做行政做了好几年。 
 We provide back-office services for several companies. 我们为好几家公司提供事务性服务。