The invention provides a tenon-type connection method for prefabricated piers and bearing platforms of sea-crossing bridges, and relates to a connection method for piers and bearing platforms. The method comprises the following steps: a pier body is prefabricated in a land prefabrication yard and transported to a field; the concrete for the bearing platform and a bearing-platform tenon is simultaneously poured; a connection gap between the lower end of the prefabricated pier body and the bearing platform is laid with a pier-foot sealing strip; the prefabricated pier body is hoisted onto the bearing platform by use of an offshore floating crane and is well positioned; and cast-in-situ seam concrete is poured into the connection gap between the pier body and the bearing-platform tenon, so as to finish connecting the prefabricated pier body with the bearing platform. The method successfully eliminates shear slip surfaces in the prior connection, increases the durability of joints, and improves the stress states of connection positions. The method can ensure that the connection of the pier and the bearing platform is concise in structure, reliable in stress, convenient to construct and simple to operate, can reduce the workload of welding steel reinforcement at sea and pouring concrete in situ, and has the advantages of greatly accelerating construction progress, saving construction cost and having remarkable economic benefit.