Legal analysis: 1. Mortgage to mortgage. Transfer the remaining loan debt to the new buyer, but it needs the consent of the loan bank first, and the seller applies to the bank for changing the borrower, loan term and other information. 2. Pay off the loan with the buyer's down payment or full payment. If the buyer's down payment or full payment is enough to pay off the loan, the seller may apply to use the above funds to repay the loan in advance. There are still some risks in the trading house that has not paid off the loan, so when signing the sales contract, both parties should communicate in advance to reduce and avoid the risks.

Legal basis: Article 61 of the Law of People's Republic of China (PRC) on Urban Real Estate Management shall apply to the land administration department of the local people's government at or above the county level for registration, and the land administration department of the local people's government at or above the county level shall issue a land use right certificate after verification.

If a house is built on the land for real estate development obtained according to law, it shall apply to the real estate management department of the local people's government at or above the county level for registration with the certificate of land use right, and the real estate management department of the local people's government at or above the county level shall verify and issue the certificate of ownership of the house.

When real estate is transferred or changed, it shall apply to the real estate management department of the local people's government at or above the county level for registration of change of real estate, and apply to the land management department of the people's government at the same level for registration of change of land use right on the basis of the changed house ownership certificate. After verification by the land administration department of the people's government at the same level, the land use right certificate shall be replaced or changed by the people's government at the same level.

If it is otherwise provided by law, it shall be handled in accordance with the provisions of relevant laws.