The invention discloses a flexible automatic assembly platform used for a hydraulic support connecting rod production line. The flexible automatic assembly platform comprises a base, wherein a bottomplate bearing platform is arranged in the center of the base and is provided with a bottom plate length centering mechanism, a bottom plate width centering mechanism and a bottom plate positioning mechanism in a matched manner; the base is provided with turnover platform supporting plates located on the two sides of the bottom plate bearing platform, each turnover platform supporting plate is in hinge joint with a main rib plate turnover platform driven by a turnover air cylinder, and each main rib plate turnover platform is provided with a main rib plate positioning mechanism and a main rib plate length centering mechanism; and a main rib plate centering combined mechanism is arranged between each turnover platform supporting plate and the base. The flexible automatic assembly platform can realize automatic centering calibration of a connecting rod bottom plate and a main rib plate, meets the relevant requirements of the hydraulic support connecting rod automated assembly welding production line, and is light, low in cost, reliable in structure and high in universality.