Fiber reinforced polymer composites are used in many engineering applications because of their low strength to weight ratio. Delamination is one of the major problems in manufacturing of the polymer composites. In this work, the delamination of acid treated basalt fiber reinforced composites was studied through drilling operation. Basalt fiber reinforced composites is prepared by using hand layup techniques with unsaturated polyester. Taguchi design of experiment was used to investigate the effects of drilling parameters such as spindle speed [2500, 2750, 3000 rpm], feed rate (0.2, 0.4, 0.6 mm/rev) and point angle (90 °, 118 °, 135 °). A series of experiments based on L9 orthogonal arrays are conducted using CNC machine and resulting delamination factor was determined. It was observed that speed and point angles are highly influencing parameters than feed rate for the delamination of the basalt fiber reinforced polymer composites.