The steel cylinder structure has the characteristics of short construction period，economy，good durability，and convenient construction. It has been applied in a project in the Guangdong-Hong Kong-Macao Greater Bay Area and a cross-river channel project in China. When there is a hard sand layer in the foundation，the vibration density effect of the sand layer will occur during the construction of the steel cylinder，resulting in the compaction of the sand layer，which brings great difficulties to the vibration settling of the steel cylinder. Forcibly installation will cause damage to the steel cylinder structure. Therefore，it is necessary to modify the sand layer and the sand layer foundation to change the vibration dense characteristics of the sand layer and make driven of steel cylinder smoothly.Through the experimental study of indoor bentonite modified sand samples，we find that：1）Bentonite can reduce the shear strength of sand very well. After modification，the cohesive force c will be improved to a certain extent，but the internal friction angle φ will be significantly reduced.2）The water-cement ratio has little effect on the shear strength of sand. The amount of bentonite has a great influence on the shear strength of mud-modified sand. 3）The mud mix ratio selected for bentonite modified sandy soil is recommended to be 5% of bentonite and the water-cement ratio of 8 to 20.