To estimate the sinking resistance and sinking force of the bucket-foundation on the composite foundation,the tide level,the vacuum degree of the compartment and the bottom elevation of the bucket-foundation structure in the sinking process are obtained through the field in-situ test,the influence law of the composite foundation on the sinking of the bucket-foundation structure is analyzed.The parameter values for estimating the sinking resistance of the bucket-foundation structure are obtained,and the estimated values of the sinking force are determined.The results show that the top elevation of sand pile in composite foundation is the key to control the installation quality,and it is suggested to select high-power vacuum equipment to ensure the controllability of sinking force.The research results can provide technical basis for the sinking construction of bucket-foundation construction.