In order to improve the safety and reliability of the double-walled steel cofferdam in the construction of bridge deepwater pier cap construction, the key working conditions in the construction process of deep-water double-walled steel cofferdam are simulated and analyzed based on the north approach bridge of Guanzhou river grand bridge. Through numerical simulation and structural stress analysis, the stress and strain changes of cofferdam structures in different construction stages are discussed. The results show that the lug plate is subjected to the greatest stress during the lowering process of the cofferdam, while in the backcover stage, the overall stress and strain of the structure are small; During the pumping and pier cap pouring stages, the stress and strain of the siding reach the maximum value. The results can provide theoretical support and practical reference for the design and construction of similar projects.