The content of the house sales contract is not illegal, as long as both parties sign and seal it, it has legal effect. 1. The house sales contract is a civil legal act and shall meet the following conditions: 1. Both parties to the contract must have the subject qualification. Both buyers and sellers of houses should be qualified to exercise their rights and assume obligations according to their own actions. (1) General subject requirements. The General Principles of Civil Law stipulates that buyers and sellers of houses should have full capacity for civil conduct. The behavior of buying and selling houses is complex, involving a large number of subject matter. The law generally prohibits restricting the participation of persons without capacity for civil conduct or persons without capacity for civil conduct, and the signed house sales contract is invalid unless it is approved by the legal representative in advance or ratified by the legal representative afterwards. (2) Thematic requirements. In order to maintain the order of housing transactions, the current laws and policies set certain conditions and restrictions on the parties to housing transactions, which must meet specific requirements. At present, in the sale of commercial housing, real estate development enterprises, as housing sellers, must have legal person business license, qualification certificate, land use right certificate, land use approval, planning permit, construction permit and so on. In the pre-sale of commercial housing, in addition to the above conditions, the pre-seller shall also hold a pre-sale permit and determine the construction progress and delivery date.