The application of the Open Caisson Method in the construction of City Canal Water Pumping Station could bring us some financial benefits including avoiding building demolishment and resident removal，and reducing some other costs．Problems such as sinking difficulity，torsional deformation and sinking error of open caisson are likely to arise by applying the Open Caisson Method on the stratified clay level of high plasticity．It discusses some related construction performances and finds out the applicable solutions to these technical problems by adjusting the internal supporting system for earth pressure and adopting comprehensive rectifying deviation method．