Abstract: To address the vibration problem caused by surface waves, a theoretical study on the vibration isolation characteristics of a periodic open trench-soil mound joint vibration isolation barrier in unsaturated soil was carried out based on the periodic structure theory and the fluctuation equation. Firstly, a single cell of the combined trench-soil mound vibration isolation barrier was selected, and the main influencing factors of the barrier's band gap characteristics were analyzed using the finite unit method. Secondly, the vibration response model of the periodic open trench-soil mound vibration isolation barrier under simple harmonic loading was established, and the effects of the geometrical dimensions of the open trench and soil-mound on the vibration isolation effect were analyzed. The results show that the joint periodic barrier in unsaturated soil has a certain width of the bandgap and better vibration isolation effect, the influence of the variation of trench size on the boundary and width of the bandgap is greater than the size of the soil mound, the width of the mound has the smallest influence on the range of the bandgap, and the other dimensions make the width of the bandgap decrease with the increase of the parameter; the number of the period of the barrier the depth of the trench has the most significant influence on the vibration isolation effect, while in the geometrical dimensions, the depth of the trench has the vibration isolation effect is the most significant and the effect of soil mound width is the least.