Carbon fiber reinforced plastics (CFRP) are typical difficult-to-cut materials because of their anisotropic mechanical properties and poor heat conductivity. Drilling is the most common process in the manufacturing of CFRP products in which delamination is the most potentially damaging defect. In the present work the delamination damage around drilled hole of multi-directional CFRP is analyzed by means of infiltration inspection method with gold chloride solution, and the effects of drill rotational rate and feed as well as drill geometry on delamination are investigated, the damage degrees in laminas near the hole entrance and the hole exit are compared. The experiment proves the infiltration method is applicable for the investigation. The results show that the nearer the distance to the hole entrance or exit, the larger the remains area of infiltration agent is; the remains mark near the hole exit is larger and more irregular than that near the hole entrance, and it has the largest length in the direction along fiber length; a chisel-free drill, a high drill rotation rate combining with a small feed brings on the decrease of delamination damage.