In order to study the distribution features of sinking resistance of caisson in soft clay area, taking the open caisson of a comprehensive pipe gallery in Ningbo as the research object, the basic soil experiments of open caisson were carried out. The results show that the basic mechanical parameters of soft soil were obtained through direct shear test and conventional triaxial test; The sinking process of the open caisson is monitored in real time, the stress mechanism of the sinking process of the open caisson is deeply analyzed, and the distribution laws of shaft wall side friction and blade foot end resistance at different depths of the open caisson are obtained. At last, based on the test data, when the open caisson foundation sinks through the silt soil layer is put forward σ_f0 changes with the sinking depth, and the corresponding empirical formula is fitted. The test results show that the lateral resistance of the caisson has not yet reached the maximum value during the sinking process, and the lateral resistance of the caisson relative to the two sides is not the same. The research results can be used to provide a reference for the same kind projects.