The invention discloses a connecting structure of a steel pipe pile and a reinforced concrete bearing platform. The connecting structure comprises the steel pipe pile embedded in the bearing platform and a plurality of vertical connecting steel bars welded to the steel pipe pile. The steel pipe pile comprises a steel pipe pile upper section pile, a lengthened steel pipe section is welded to the top of the steel pipe pile upper section pile, an annular connecting plate is horizontally arranged on the top surface of the lengthened steel pipe section, and the vertical connecting steel bars are welded to the surface of the annular connecting plate at intervals. The connecting structure not only is easier to construct and has higher firmness in connector connection, but also greatly reduces field welding workload.