The penetration process of the large-diameter steel cylinder in sandy soil was stimulated with a three-di-mensional particle flow code (PFC3D) based on the discrete element method (DEM)． A scaled model based on the principle of the centrifuge and a full-scale model with adjusting the micro-parameters were developed to analyze the sliding friction force distribution of the cylinder during installation and the contact force chain of soil particles．The DEM model was validated by comparing the simulated results with theoretical values and reported experimental phenomena． The effects of micro parameters of particles and contacts on side friction were studied through further parametric analysis． The study results show that，unlike pile penetration，there is almost no soil-plug effect during penetration process of large-diameter steel cylinder． Besides，the inside friction is half of the total friction，and the side friction has the effect of friction fatigue during installation． Compared with the scale model，the full-scale mo-del with adjustable micro-parameters has better calculation efficiency． There is a close relationship between the side friction and micro parameters．