Based on the elastic beam theory, the Boussinesq solution and the layered foundation model, considering box foundation with inner columns as a composite structure of elastic slabs and columns, a semi-analytical and semi-numerical method is developed to analyze interaction between box foundation with inner columns and ground by studying force balance and displacement compatibleness of slabs, ground and columns. Numerical simulation examples show that there are reliable precision and less unknown variables for this method. It is convenient to be applied in practical engineering calculation.