Abstract: Based on the theory of elastic beam and Boussinesq solution,a semi-analytical and semi-numerical method,which made use of compatible analysis of force and displacement between grillage beams and ground,was developed to analyze interaction between grillage foundation beams and subsoil with considering grillage foundation beams as a composite system of beams in two directions. The results converged well and had credible precision. Numerical examples proved that this method had good preciseness and practicality. And the influencing factors of interaction between grillage beams and subsoil were discussed.