Membranes composed of dextran (DEX) and poly(L-lactide-co-epsilon-caprolactone) (PLCL) as ultrafine core/shell fibers for loading platelet-derived growth factor-bb (PDGF-bb) were produced by coaxial electrospinning. The morphology and core/shell structure of the DEX/PLCL fibers containing PDGF-bb were investigated by scanning electron microscopy and transmission electron microscopy. The loading amount of PDGF-bb in the DEX/PLCL membrane prepared at 0.1 ml/h of the inner solution flow rate (DEX/PLCL-1P) was much lower than that in DEX/PLCL-2P and DEX/PLCL-3P obtained at 0.2 ml/h and 0.3 ml/h inner solution flow rate, respectively. All three membranes showed obvious burst release of PDGF-bb in the first 2 days, and then the release behaviors were smoother and steadier. They all kept a fibrous morphology during the whole release period of 28 days. Studies on adhesion, proliferation and morphology of the vascular smooth muscle cells on the fibrous membranes of DEX/PLCL-1P, DEX/PLCL-2P and DEX/PLCL-3P, as well as PLCL and DEX/PLCL suggested that DEX/PLCL membranes containing PDGF-bb protected in the core of ultrafine fibers could positively promote cell attachment, and their cell activities were significantly higher than those of PLCL and DEX/PLCL membranes without PDGF-bb. The DEX/PLCL-2P membrane with fine core/shell structure of fibers would be the best choices for further applications.