A current development trend of the industrial equipment is ultra-large scale. The construction, transportation, and installation of these equipments require ultra-large tonnage lifting equipments. At present, domestic ultra-large tonnage lifting equipments, particularly for special purpose are still immature, unable to meet requirements of the lifting of ultra-large structures. Based on the need of ultra-large steel structures (offshore oil platforms) lifting, using strength theory and finite element analysis, a continuous lifting mechanism for the lifting of ultra-large structures was designed in this article. The continuous lifting mechanism consists of two parts: the mechanical support structures which was designed in this article, and the hydraulic system. The main characteristics of the mechanism are: the framing truss structure assures large height lifting; and the accumulated of synchronous blocks achieves large height lifting.