is there any Logistics service to send extra luggage when you've got more than required KGS

if you luggage is more than 20kg but still less than 50kg, you can still arrange it as checked luggage but need to pay extra fee for the extra luggage. The price should be 1.5% of the full price of the economy class per kg. For example, if the full price ticket for your trip is CNY1000, then you need to pay CNY15 per kg for extra luggage weight.