Extensional flow has been shown to be more efficient solution for improving the dispersion of nano-composites as compared to shear flow. One of the production processes of nano-composites is melt extrusion with corotating twin screw extruder (TSE) which is superior in terms of productivity and mixing performance. Our objective is the optimization of Blister Disk geometry which has many holes for improving the dispersion of nano-composites. The holes were drilled through the Blister Disk seal ring segments to create extensional flow in TSE. However, it was difficult to evaluate the mixing effect of Blister Disk because the flow patterns are complex in TSE, and there is some possibility of no flow through the holes of Blister Disk. To evaluate the dispersion effect of only holes, fundamental evaluation equipment was developed. Firstly, the stress magnitude was investigated for each elongational flow and shear flow by changing the geometries (e.g., hole numbers, hole diameter and hole width) with 3D numerical simulation. Then, the dispersibility variation of polypropylene (PP) and Carbon Nano Tube (CNT) nano-composite was investigated by using various geometries of Blister Disk with fundamental evaluation equipment.