Abstract: The shear strength parameters obtained by the triaxial test are indispensable parameters for the geological survey of major projects. According to the geotechnical test method standard, the UU triaxial test was carried out on the saturated thick soft soil in Wenzhou, and the principal stress diffenrence-axial strain relationship curves, the shear strength envelope curves, as well as the shear strength parameters of the soil were obtained. There are a series of problems during the test, such as difficulty in preparation of the sample, low shearing efficiency and high requirements on the test conditions. Therefore, based on the results of UU triaxial test, FLAC3D numerical analysis software was used to carry out the numerical simulation test for UU triaxial test of thick soft soil. The results show that the variation tendency of the principal stress difference-axial strain curve and the shear strength envelope curve is basically consistent between the numerical simulation test and the laboratory test. Although the phenomenons of slightly higher cohesive force and slightly lower internal friction angle appears, they are all within the range of test error. The numerical simulation test can simulate the UU triaxial test of thick soft soil well, and obtain shear strength parameters, providing references for similar soils to obtain shear strength parameters through numerical simulation test.