I would like to send my small carry-on suitcase including clothes (max. 10kg, 50x20x40cm).

The fastest way is to send it through the air mail. One can receive the parcel in about one month, but the expense is quite high at around CNY800. Surface mail is the cheapest method. The fare is about CNY300 but it should take a longer time to reach the destination. You may choose according to your own situation.