1, the actor has corresponding capacity for civil conduct;

2. The intention is true, and there is no coercion or other prohibited circumstances stipulated by law;

3, do not violate the mandatory provisions of laws and administrative regulations, do not violate public order and good customs;

4. The information of the parties is clear, the contents are clearly written, and both parties sign or press their fingerprints.

Legal effect of written evidence:

1, the contents of written evidence should be true, and there can be no false records;

2. The form of written evidence shall be legal and shall not violate the law;

3. The signing of written evidence must be the expression of the true meaning of the parties, and there shall be no coercion or fraud;

4. The parties to written evidence shall have corresponding capacity for civil conduct, and the written evidence signed by minors or persons with limited capacity for civil conduct may be restricted;

5. The matters involved in written evidence shall not violate the mandatory provisions of laws and administrative regulations.

To sum up, in order to be effective, written evidence must meet the following conditions: the actor has corresponding capacity for civil conduct, the intention is true, non-coercive and illegal, the content must not violate laws and regulations and public order and good customs, the information of the parties must be clear, the content must be clearly written, and both parties need to sign or seal for confirmation.

Legal basis:

People's Republic of China (PRC) Civil Code

Article 490

If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.

Article 49 1

The parties conclude a contract by means of letters, data messages, etc. It is also required to sign a confirmation letter, and the contract is established when the confirmation letter is signed. If the information of a commodity or service released by one party through information networks such as the Internet meets the conditions of the offer, the contract is established when the other party successfully selects the commodity or service and submits the order, unless otherwise agreed by the parties.