The topology optimization method can find the best path of the load transmission and the best type of the load bearing on the premise of ensuring the requirements of the design specifications. The compromise programming method is a method commonly used in the topology optimization deign of the structure under multiple operating conditions. However, the designers need to perform topology optimization trial calculations under different volume fraction constraints during the topology optimization design, which often costs more time. An improved compromise programming method is then proposed to save time. The multi-operating-condition topology optimization design is carried out for the longitudinal frame of a cantilever platform in the offshore engineering structure based on the secondary development of the HyperMesh software. A clear longitudinal frame configuration is given from the perspective of structural design according to the final topology optimization configuration.