What should I do if I have something urgent to return to China on my way abroad?

Buy a plane ticket to return to China.

I don't know what your reason is. If it's a visa, don't worry. In fact, a visa is a ticket issued to you by other countries and valid for a specified period of time. During the validity period, your entry and exit will not be restricted.

It is more expensive to buy air tickets temporarily, but you can still use these websites to brush air tickets abroad, so don't worry too much.