Nowadays,more and more old wharf need to be deepening and strengthening to meet the requirement of large ship displacement due to their service life or business development,but the space for updating is limited.Therefore,it is necessary to study the structural type of narrow and long wharf with limited space.This paper analyzed the geological change and the limitation of the original design scheme in one project,combining with the trial pile,and adjusted the design from elevated pile and beam-slab structure into pier platform structure.Theoretical calculation and construction results show that this design optimization can adapt to the complex geology of narrow and long structure,and it has reference significance for similar reconstruction projects.