This paper focused on the investigation of mechanical, twist drilling performance and microstructural analysis in aluminum foil reinforced sisal flax epoxy composite. Six combinations of composite (SF1–SF6) were fabricated by hand layup method with two different orientation of circular (φ = 5 mm) geometrical patterns in aluminum foil (thickness 0.024 mm) as structural reinforcement. The mechanical properties were determined by the tensile, flexural, impact, and hardness investigation with ASTM test specimens. The machinability of the composites was studied through twist drilling operation (8 mm), and the drilling experiments were designed by the design expert 11.0. The analysis was performed on a CNC milling machine (VF-30 CNC VS) vertical milling center with the different process parameters like spindle speed (500–2000 r/min), feed rate (0.05–0.25 mm/min), and hole pitch (20, 40, and 60 mm) in sliding dry environments at room temperature. The fractured composite samples were examined through a scanning electron microscope to determine the fiber pullout, deboning, and voids between the reinforcement and matrix. The obtained results were shown that the sample with 45° staggered hole with 60 mm hole pitch (SF6) composite holds the excellent mechanical properties like tensile strength (31 MPa), flexural strength (76 MPa), impact strength (1.5 J), and hardness value (23 VHN) compared to other combinations. The effect of hole pitch and spindle speed significantly affects the circularity error. © The Author(s) 2020.