If you've already missed your flight, go first to the personnel of the Airline that caused you to miss your flight.

They should help you get rebooked with a new ticket.

They may also help with some of the extra expense and/or provide you with a meal or hotel voucher if necessary.

Hopefully, for good customer service, they will at least assist you. But if you have booked your flights too close together, within an hour or two, you might find you have created your own problem and the Airlines won't cover your costs.

You'll need to check with the individual Airlines in China about the minimum check-in time to connect to another flight.