Abstract: A three-dimensional discrete-continuous coupling numerical model is established to simulate the bearing capacity of recycled aggregate dynamic compaction columns. The bearing deformation mechanism, column failure mode and load transfer law are studied. The bearing capacity of recycled aggregate columns with different column lengths and different porosities is analyzed. The results show that the recycled aggregate column exhibits bulging deformation in the horizontal direction when it is destroyed, and the bulging deformation is mainly concentrated in the depth of 3 times the column diameter. The soil around the column forms a continuous shear slip surface through the surface, and the surface will have uplift. The bottom 3 times the column diameter diameter of the full-length column does not carry the load and the effective length is 7 times the column diameter. With the decrease of porosity, the bearing capacity of the recycled aggregate column is gradually improved.