Abstract: Gravel-soil core wall structure is often used in ultra-high earth-rock dams to enhance the ability of coordinate deformation of seepage control body,and the gravel-soil interbedding thickness is an important index to determine gravel content of gravel-soil.In the conventional method,the difference of gravel content is not considered,which may lead to the low accuracy of gravel content control.In this paper,the formula of dynamic adjustment process of gravel-soil interbedding thickness was proposed by the conservation principle of gravel content,and it was verified that the dynamic adjustment method was more accurate than the conventional method by the comparative test of Lianghekou Hydropower Station.In order to reduce the restriction on the project progress caused by the increase of test frequency in the dynamic adjustment method,the allowable fluctuation range of gravel content was determined based on the sensitivity analysis principle,and the measures of re-exploration of material yard,pre-mining detection,and thickness of new layer being determined by detection data of pre-layer were used to strengthen the process connection.Finally,considering the factors of winter and rainy season,the construction sequence of gravel-soil interbedding can be adjusted flexibly to ensure the quality of gravel-soil.