Aiming at the local scouring problem in the construction of large open caisson foundation of typical river-spanning bridge in the lower reaches of the Yangtze River, combined with the geological characteristics of riverbed and hydrodynamic conditions, based on the measured data of riverbed topography, the local scouring characteristics of open caisson foundations of Taizhou Yangtze River Bridge, Changtai Yangtze River Bridge and Shanghai-Suzhou-Nantong Yangtze River bridge under different sinking construction conditions are analyzed. The results show that under the condition of direct sinking construction of open caisson foundation, local scouring is easy to lead to the height difference between the upstream and downstream riverbed of the open caisson, which brings risks to the open caisson construction. Under the conditions of riverbed pre-protection and riverbed pre-excavation combined with riprap protection, the sinking construction of open caisson is relatively safe. The relevant achievements can provide reference for the construction of large-scale open caisson in river-spanning bridges.