A traditional Chinese drug "Yunnan Baiyao" is used as an additive in poly(butylenes succinate-co-bytylene terephthalate) (PBST) solution, which is a kind of biodegradable aliphatic-aromatic copolyesters, to produce microspheres with nanoporosity by electrospinning; the tunable size of nanoporosity can be controlled by changing the voltage applied in the electrospinning process.