As an economic and practical foundation treatment method, vibroflotation gravel piles are specially designed for weak strata, the quality control of which are of great significance, and the diameter of the gravel pile is one of the core elements of the control of pile forming process.Based on the calibration of macroscopic and mesoscopic parameters of the gravel pile and soil, the pile forming process of the vibroflotation gravel pile is analyzed and the main pile forming processes, such as hole forming and cleaning, filling and vibroflotation compaction are simulated using the discrete element method. In the meantime, the pile diameter prediction is carried out. The results show that the particle flow discrete element can simulate the flow between the gravel and soil in the process of vibroflotation, and the model reflects the actual transition interface between gravel and soil; in the process of retaining vibration, the porosity of the soil around the gravel and densified section decreases gradually, indicating that the vibroflotation gravel pile has an obvious compaction effect on the soil around the pile; because the discrete element method can simulate the interaction between the gravel and soil, the calculated fluctuation of pile diameter and pile shape is more reasonable than that of the calculation method of conventional formulas.