What is the baggage regulations when flying inside China?

Regulation: A passenger should arrive at the airport for check in at least 90 minutes prior to departure of the flight. Passengers are not allowed to carry liquids onboard the aircraft, but they can be included with checked baggage. One item of cosmetics is allowed provided it is not in excess of 100 ml. It must be put into a separate package after security inspection.

Prohibited Items: The following items are prohibited and cannot be carried in checked or carry on luggage: - Flammable, explosive, corrosive, poisonous, radioactive, polymerizable and magnetized materials. Passengers are forbidden to carry arms, sharp or lethal weapons during flight. These items will be confiscated by the security if detected. Lighter and matches can not be included in carry-on baggage either.

Carry-on baggage: As of May 1st, the maximum Carry-on baggage allowance for each economy class passenger is only one piece of 5kg, and passenger traveling first-class is allowed 2 separate articles of 5kg each. The piece should be no larger than 20x40x 55cm. Carry on baggage in excess of the limit is subject to the excess baggage fee and must be carried as checked baggage.

Free baggage allowance: Adult and children (economy class) are entitled to a free checked baggage allowance of 20kg. For passengers of business class, the allowance is 30kg while first class is 40kg. The maximum weight of checked baggage is 50kg. Each piece should be within 40x60x 100cm. No free baggage allowance is granted to infants. Excess baggage is charged at the rate of 1.5% of the full price of the economy fare per kg
For example,
Beijing to Xi'an: RMB1050, so RMB16 per kg
Xian to Chonquing: RMB700, so RMB11 per kg

Check-in Baggage: Groups of 10 or more traveling together are able to combine their baggage allowance if they check in together.