Legal Analysis: Generally speaking, you don't need a guarantor when you apply for a student loan, but you need co-borrower as a guarantor because the student has no source and ability to repay. If you need your sister to come forward, then your sister needs to meet the following conditions:

1. The household registration of the parents or legal guardians of the borrowing students must be consistent with the household registration of the borrowing students before they enter school.

2. If the parents of the borrowing students lose their ability to work or civil conduct due to special circumstances such as disability or illness, other immediate family members of the borrowing students can be regarded as co-borrower.

3. If the borrower is an orphan, other legal guardians or natural persons with full civil capacity who voluntarily share the repayment responsibility with the borrower are co-borrower.

When co-borrower is not his parents, he must be between 25 and 60 years old.

5. If co-borrower applied for a student loan before and didn't pay it off, it can't be used as a co-borrower for other borrowing students.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 667 A loan contract is a contract in which the borrower borrows money from the lender, repays it at maturity and pays interest.

Article 668 A loan contract shall be in written form, unless otherwise agreed between natural persons.

The contents of a loan contract generally include terms such as loan type, currency, purpose, amount, interest rate, term and repayment method.

Article 669 When concluding a loan contract, the borrower shall provide the true information about the business activities and financial status related to the loan according to the requirements of the lender.