In this paper, given the shortcomings of jellyfish search algorithm with low search ability in the early stage and easy to fall into local optimal solution, this paper introduces adaptive weight function and elite strategy, improving the global search scope in the early stage and the ability to refine the local development in the later stage. In the numerical study, the benchmark problem of dimensional optimization with a 10-bar truss structure and simultaneous dimensional shape optimization with a 15-bar truss structure is adopted, and the corresponding penalty method is used for constraint treatment. The test results show that the improved jellyfish search algorithm can provide better truss sections as well as weights. Because when the steel main truss of the large-span covered bridge is lifted, the site is limited and the large lifting equipment cannot enter the site, and the original structure does not meet the problem of stress concentration and large deformation of the bolt group, so the spreader is used to lift, and the improved jellyfish search algorithm is introduced into the design optimization of the spreader. The results show that the improved jellyfish algorithm can efficiently and accurately find out the optimal shape and weight of the spreader, and through Midas Civil simulation, the spreader used can meet the requirements of weight and safety.