Does the copy of the purchase contract have legal effect? The reply to your question is as follows: First, the Housing Sales Contract signed by you and the developer is an effective evidence to prove that you and the developer have established a civil rights and obligations relationship for housing sales. 2、 If a dispute arises due to the provisions of the Housing Sales Contract or the performance of the contract, the original copy of the sales contract shall be provided as evidence, and only the copy does not meet the evidentiary requirements of litigation evidence, except that the other party recognizes the authenticity of the copy. 3、 If it is necessary to return the original contract, first make a complete copy of the original for backup, and ask the developer to write "for what reason, when and when to return the original, this copy is the same as the original" on the copy, and affix the official seal. The developer must negotiate with you to modify the contract terms. After the contract is modified, you should return the modified contract in time. 4、 The following legal articles are provided for your reference: Article 49 of the Several Provisions of the Supreme People's Court on Evidence in Civil Procedure: When cross examining documentary evidence, material evidence, audio-visual materials, the parties have the right to require the original or original evidence. Except in any of the following circumstances: (1) it is really difficult to produce the original or the original, and the people's court permits the production of duplicates or reproductions; （2） The original or original does not exist, but there is evidence to prove that the copy or reproduction is consistent with the original or original.