The periodic dry and wet changes of the fluctuation zone in the Three Gorges Reservoir area cause water and soil loss on the bank slope，resulting in soil exposure and less vegetation coverage and making ecological restoration difficult.Under the combined action of external rainfall and waves，the surface soil of the bank slope in the fluctuation zone is scoured and eroded，resulting in intensified erosion and soil loss.Taking the soil bank slope in the fluctuation zone in the Three Gorges Reservoir area as the research object，this paper analyzes the erosion weight under the combined action of rainfall and waves and studies the protection performance of the terra block mat structure under the composite erosion.The experimental results show that the average erosion weight of wave factor and rainfall factor is 71.23% and 49.56%，respectively.Wave is the main erosion factor in composite hydraulic erosion.Terra block mat has great erosion resistance and can reduce the average soil loss of about 65.2% in composite hydraulic erosion，and adding a stone cage net structure can improve erosion resistance by about 20%.It has guiding significance for the analysis of similar soil erosion and the selection of revetment structures.