According to Article 35 of the Contract Law, if the parties conclude a contract in the form of a contract, the contract shall be established when both parties sign or seal it. As far as the parties are concerned, they are nothing more than natural persons, legal persons and other organizations. When a natural person concludes a contract, the natural person who concludes the contract generally has to sign or seal it; When a legal person or other organization concludes a contract, it is generally signed by the legal representative of the legal person or the person in charge of other organizations or stamped with the official seal of the unit. There is no clear stipulation in China's contract law on what kind of seal legal persons and other organizations should affix. In reality, there are many kinds of official seals of legal persons and other organizations, including special seals for contracts, special seals for finance, administrative seals and official seals of various departments. Generally speaking, both the special contract seal and the administrative seal can be used as the contract seal. As for the effectiveness of the special financial seal and the official seal of each department, it depends on the specific situation. If only financial issues such as debt amount (inter-enterprise statement) are proved, then the financial seal is also valid.