First: You have to decide which patent to buy. Is it authorized? You can go to the national intellectual property network to find those published patents, or you can go to those patent transfer networks. Bikeyi。 Com has many patents in various fields.
Second, specific purchase matters can be negotiated with the patentee through the agency. Including: understanding of patented technology, price negotiation, etc. Agree on the specific transfer right, whether to transfer the whole patent right or exclusive license.
Third: You can handle the transfer formalities in China National Intellectual Property Administration by yourself or with a patent agency. It is suggested to find a patent agency here, because they know more about the specific matters.