legal ground
Article 397 of the Civil Code
Where a building is mortgaged, the right to use the construction land occupied by the building shall be mortgaged together. Where the right to use construction land is mortgaged, the buildings on the land shall be mortgaged together. If the mortgagor fails to jointly mortgage in accordance with the provisions of the preceding paragraph, the mortgaged property shall be regarded as joint mortgage.
Article 399
The following properties shall not be mortgaged:
(1) Land ownership;
(two) the right to use collectively owned land such as homestead, private plots and private hills, except those that can be mortgaged according to law;
(3) Educational facilities, medical and health facilities and other public welfare facilities of non-profit legal persons established for the purpose of public welfare, such as schools, kindergartens and medical institutions;
(4) Property whose ownership and use right are unknown or controversial;
(5) Property that has been sealed up, detained or supervised according to law; Other properties that may not be mortgaged according to laws and administrative regulations.