The anchor foundation is the main bearing structure of suspension bridges and its deformation and stability are very important issues. For the south-anchor foundation of the Taizhou Bridge,the stratum and structure model of three-dimensional is established. Using large-scale numerical software Flac3D and surcharge analysis method, the deformations of the anchor foundation with different surcharge coefficients are studied based on the assumption that the values of surcharge are changed proportionally with the cables tension. The results show that the values of numerical simulation are close to the measured values under the design value of the cable tension. The linearly increasing relationship between the maximum deformation of anchorage foundation and value of the surcharge coefficient is obtained when the surcharge coefficient is less than 3.5. The nonlinearly increasing relationship between the maximum deformation of anchorage foundation and value of the surcharge coefficient is obtained when the surcharge coefficient is greater than 3.5. When the value of the surcharge coefficient is 3.81 times of the design value of the cables tension, the maximum horizontal displacement of the anchor foundation reaches the limit value. Based on the soil plastic zone distribution range and deformation control requirements of the anchorage foundation, the numerical value of surcharge safety for the south-anchor foundation of the Taizhou suspension bridge is 3.81. The reference conclusions for the stability evaluation of the Taizhou bridge project are provided.