Bi-modal porous material is considered to have superior physical and tissue-inducing properties. This study reports on the fabrication of bi-modal porous poly(epsilon-caprolactone) (PCL) scaffolds using two-step depressurization supercritical CO2 foaming process. In a single process, large pores over 100 mu m nucleated in the slow depressurization step, and coalesced during holding stage; small pores below 40 mu m were formed in the rapid depressurization step. Investigation on foaming parameters demonstrated that soaking time longer than 0.5 h was necessary to produce bi-modal pores. It was noted that the holding stage had a significant impact on the final pores. In particular, intermediate pressure would affect the plasticizing capabilities of CO2 to increase (5-7 MPa) or decrease (7-12 MPa) pore size. In all, bi-modal porous PCL foams with around 80% porosity were produced, and this work provided a potential reference to efficient design of bone tissue engineering scaffolds.