No stamp duty is required.
The Interim Regulations on Stamp Duty lists 10 types of contracts that are subject to stamp duty. Gift contracts are not among them, so they do not need to pay.
However, if the gift contract involves the transfer of property rights, such as property ownership, copyright, trademark exclusive rights, patent rights, and proprietary technology rights, the transfer documents should be the property rights transfer documents. Pay stamp duty at 0.05% of the stated amount. Donations of property to governments, social welfare units, and schools are tax-free.