According to the relevant provisions of China's Civil Code, if the parties conclude a contract in the form of a contract, the contract is established when the parties sign, seal or press their fingerprints. Directly juxtaposed with the way of signing and stamping by fingerprints, it has become a legal way of signing contracts. Therefore, signature, seal and handprint are equal and equally divided, which constitutes the situation of "three pillars" in the way of contract signing.

The use of the seal is equal to the signature of the seal owner, and the effectiveness of the seal is equal to the effectiveness of the signature. The reason why the seal has the function of proof is that the seal can replace, can repeatedly replace the signature, and sometimes has the function of saving labor. Because the seal is easy to forge, the nominal owner of the seal is easy to separate from the actual controller, and the probative power of the seal is essentially lower than that of the signature.

More attention should be paid to signature in trading activities, because the certainty of the relationship between signature and signer is far greater than that between seal and signer. As long as the other party signs in person, the validity and probative force of his signature can be guaranteed to a considerable extent.