Tissue engineering scaffolds are applied to temporary frameworks to support the regeneration of tissues. Highly porous and interconnected 3D structures are crucial elements for scaffolds since they can support for the mass transport of cell nutrients and waste. Supercritical foaming technology is an environmentally-friendly and solvent-free way of manufacturing porous scaffolds. In this research, highly porous interconnected poly(ɛ-caprolactone) (PCL) scaffolds combined with supercritical carbon dioxide (CO2) foaming and a polymer leaching process were fabricated by blending PCL with water-soluble poly(ethyleneoxide) (PEO) as a sacrificial material. The effects of phase morphology of PCL/PEO blend on foaming behavior and pore morphology were firstly investigated. The incorporation of PEO not only facilitated the foaming of PCL by increasing its viscosity, but it also improved the porosity and interconnectivity of the post-leached PCL scaffolds. The open pore content up to 91% and fibrillated porous scaffolds were obtained after leaching process because of two different cell-opening mechanisms. Cell-opening on surface of scaffolds is one difficult point to prepare porous materials. In the end, a novel method for improving surface porosity was described as well to set up the so-called outer and inner porous PCL scaffolds. The information gathered in this study may provide a theoretical basis for research into porous tissue engineering scaffolds.