Numerical analysis of drilling damage caused by drill's thrust load is investigated by using a 2D elasto-plastic FEM analysis with a multi-scale mesh modeling. Hocheng et al. (2003) set up theoretical models to predict critical thrust forces at the onset of delamination failure when drilling process. A drill bit pushes composite plates with a thrust force which is mostly related with drill's tip geometry, i.e. a twist drill's chisel edge, and this thrust force is closely related to the drilling damage. However, from the actual drilling results, a delamination failure is just one of the failure types among fiber breakage, matrix crack, and delamination. Also, various combinations of fiber and matrix materials result different drilling damage, such as interlaminar toughened CFRP suppress delamination, even drilling process. Since the material properties have a strong effect on composite drilling results, the FEM code also considers material characteristics. The code was first validated with simple experiment result. By using 2D like specimen, failure mechanism for interlaminar toughened CFRP is understood. The main failure characteristic was closely related to the matrix crack, plastic deformation, than delamination failure. The crack gradually increased inside the matrix, and simulation also follows these phenomena. Then, various types of drilling cases are numerically investigated, such as different sizes of chisel edge, various point angles, and even material itself. Results show that sharp chisel edge with small point angle drill bits, close to the composite torque drill in the market, are effectively reduce the size of damage. Effect of material properties, with or without interlaminar toughened layered, are investigated and toughened layered CFRP suppress more failure than CFRP with delamination failure.