With the purpose to decrease the crystallinity of poly (e-caprolactone) (PCL), a small amount (8.5 mol%) of 2,2-dimethyltrimethylene carbonate (DTC) was added to copolymerize with epsilon-caprolactone (CL) using lanthanum tris (2, 6-di-tert-butyl-4-methylphenolate) (La(OAr)(3)) as catalyst. The produced polyester P(CL-co-DTC) (PCD) was well-characterized by H-1-NMR, SEC, DSC and WAXS. The results showed random copolymer PCD was synthesized. DSC and WAXS results proved PCD had a much lower crystallinity (chi(c) = 28.1%) compared to that of PCL (chi(c) = 44.7%). PCD, as well as PCL homopolymer containing 8 wt% salicylic acid as a model drug was electrospun into ultrafine fibers with the diameter around 1 mu m and further submitted to in vitro drug release test. The results showed that the PCD electrospun mat exhibited a controlled drug-release behavior while the PCL one displayed a burst-release behavior. The DSC and WAXS results showed PCL electrospun fibers had a much higher crystallinity (chi(c) = 79.3%) than that of PCD electrospun fibers (chi(c) = 40.3%) and this explained the difference of drug-release behaviors of the two electrospun mats. It was the non-crystalline domains involved in PCD that facilitated the compatibility between the polymer matrix and salicylic acid and allowed the drug to be released in a controlled way through the thermal motion of the polymer chain. This study provided a strategy for a better drug inclusion and release behavior by lowering the crystallinity of matrix material.