As an example, I guess, scroll down to the reasons allowable and documents required for citizens buying/sending foreign money...
http://www.icbc.com.cn/icbc/personal%20banking/crossborderfinancialservices/icbccurrencyexchange/buyfxpersonal/Purchase Reasons
Documents Required
Overseas study at one's own expense (including all persons going abroad for study or training at their own expenses)
Pay for the tuition fees (scholarship excluded) of the first academic year /semester
Customer shall provide originals and copies of common passport and valid visa, admission letter from the overseas school, and proof of fees (Faxed copies of admission letter and proof of fees or copies downloaded from internet are also acceptable if the original copies cannot be provided. The same below).
Pay the living expenses of the first academic year/semester
Customer shall provide originals and copies of common passport and valid visa, admission letter from overseas school, and proof of living expenses issued by school/embassy/government (original copies or faxed copies or copies downloaded from internet).
Pay the tuition fees (scholarship excluded) of the second academic year/semester and after
Customer shall provide copies of common passport and valid visa, proof of fees for the year/semester.
Pay the living expenses of the first academic year/semester
Customer shall provide copies of common passport and valid visa, certificate of studying (student card) and proof of living expenses issued by school/embassy/government (in original copies or faxed copies or copies downloaded from internet).
Can only get student visa after paying for certain security deposit
Customer shall provide common passport, admission letter and proof of tuition fee issued by the overseas school, proof of living expense fee issued by school/embassy/government in original copies or faxed copies or copies downloaded from the internet. ID Card and household register shall also be submitted.
Overseas medical treatment
Customer shall provide originals and copies of common passport and valid visa (or visa endorsement), proof of medical treatment issued by the domestic hospital with doctor's opinion and proof of fees (in original or faxed copy) issued by the overseas hospital.
Overseas training
Customer shall provide originals and copies of common passport and valid visa (or visa endorsement) and proof of fees (in original or faxed copy) for overseas training.
Personal membership fee of international organizations abroad
Customer shall provide payment notice (in original or faxed copy) issued by international organizations abroad and ID Card or household register.
Overseas mail
Customer shall provide advertisement or order or other proof of charge (in original or faxed copy or copy downloaded from the internet) and ID Card or household register.
Emergency assistance to direct relatives abroad
Customer shall provide proof of relation issued by authorized department or notary agency, documents (in original or faxed copy) related to the assistance and ID Card or household register.
Overseas consultancy
Customer shall provide written application, identity document, contract (agreement), invoice (payment notice) and tax payment documents.
Other fees for service and trade
Written application, identity document, contract (agreement), invoice (payment notice) and tax payment documents shall be provided.
Trade in goods and other related fees
Customer shall provide written application, identity document, Customs Declaration for Import Goods; contract (agreement), invoice (payment notice) (in original or faxed copy or copy downloaded from the internet).
Pay overseas spending or expenses without credit cards
Customer shall provide written application, identity document and proof of overseas spending or expenses. The customer shall apply for the purchase of foreign exchange within two month after returning from abroad.