If you want to work or teach in China and you are currently outside China, this is the outline of steps for documentation and authentication.
prepare original documents for:
highest education diploma and your teaching license
police certification that you have no criminal background, validated the last six months
reference letters from your previous employer(s)
photocopies of your passport photo and signature pages
photocopy of your contract, provided by your employer in China
Home Country Authentication
if you are currently residing in China, this process and the requisite materials could be somewhat different depending on which visa you currently hold.