Legal analysis: 1. In principle, co-borrower should be the parents of the borrowing students. If the parents of the borrowing students lose their ability to work or have civil capacity due to special circumstances such as disability or illness, other immediate family members of the borrowing students can be regarded as co-borrower; If the borrower is an orphan, co-borrower is another legal guardian or a natural person with full civil capacity who voluntarily shares the repayment responsibility with the borrower. 2. co-borrower's household registration and students' pre-school household registration are in counties (cities, districts). For example, if co-borrower is not the parent of the borrowing student, he is in principle between 25 and 60 years old; Borrowing students who have obtained loans from the Development Bank cannot be co-borrower as other borrowing students in principle. In addition, there is a special case where students are orphans or have no legal guardians. In this case, students can invite other close relatives as co-borrower. Co-borrower, as a student's next of kin, must meet the following conditions: 1, and the age must be between 20 and 60. In the process of handling, co-borrower is over 60 years old and needs to be replaced; 2. People who get student loans from students' places of origin cannot be regarded as co-borrower of others in principle; 3. co-borrower should try its best to have a certain repayment ability.

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 680 It is forbidden to lend at high interest, and the loan interest rate shall not violate the relevant provisions of the state. If there is no agreement on the payment of interest in the loan contract, it shall be deemed that there is no interest. If the loan contract does not specify the method of interest payment, and the parties cannot reach a supplementary agreement, the interest shall be determined according to the local or the parties' trading methods, trading habits, market interest rates and other factors; Loans between natural persons are regarded as having no interest.