Overstay: exceeding the validity of your Chinese visa
If you stay on Chinese territory longer than the validity of your Chinese visa, you will not be allowed to leave the country.
You will have to pay a fine, which increases per additional day of overstay. To leave the country, you will also need a new exit visa. You will need to go to the Exit and Entry Administration Office of the local Public Security Bureau (PSB): Beijing - Shanghai - Guangzhou. Do take into account that issuance of such an exit visa may take up to 20 working days. The Embassy or Consulate General is not authorized to intervene in the standard procedure. Consequently, you may have to postpone your flight. It is also not excluded that you will be retained for maximum 15 days and that you are deported hereafter. In addition, an entry ban can be imposed for up to 5 years.