Abstract: The vibration isolation effects of an open trench-WIB barrier on the vertical harmonic loads are studied by using the combined method of model tests and numerical simulations. Firstly, the vibration isolation effects of the open trench-WIB barrier and the open trench are compared. The experimental results show that the vibration isolation effects of the combined barrier are better than those of the open trench barrier at each excitation frequency and the most obvious in the low frequency. Then, combined with the perfectly matched layer absorption boundary, a three-dimensional finite element model is established using the COMSOL to set up the open trench-WIB barrier in an elastic half space under harmonic loads. The vibration isolation effects are evaluated through the acceleration amplitude attenuation coefficient, and the influences of the geometric parameters of the combined barrier on the isolation effects are studied. The results show that the geometric parameters of the combined barrier have a great influence on the vibration isolation effects. The larger the depth of the open trench, the better the isolation effects, but different in the low frequency. Meanwhile, the larger the depth and length of the WIB, the better the vibration isolation effects of the combined barrier. Moreover, the open trench-WIB barrier is more suitable for the near-field active vibration isolation.