A new oxidized corn starch-based antimicrobial material (OI) was successfully produced by linear grafting of indoleacetic acid monomer (IAA) on oxidized corn starch (OCS) through a simple "one-pot" method. OI was then further blended with biodegradable polycaprolactone (PCL) to produce oxidized corn starch-polycaprolactone based antimicrobial film (PO). The chemical structures and performance characteristics of the prepared OI and PO films were characterized by FTIR, UV-vis, and XRD. The results showed that IAA was combined with OCS mainly by esterification reaction, and the substitution degree reached 60%. After compounding OI with PCL, the crystallinity of the prepared PO films was significantly decreased. With the increase of OI content in the composite films, the prepared film materials decreased in light transmission, increased in tensile strength, and slightly decreased in contact angle. Especially, when the OI content was 10% (based on the total mass, the same below), the produced PO-10 showed good biocompatibility, non-leachability, and antibacterial activity. According to the disk diffusion test, the minimal inhibitory concentration of the produced antibacterial material was 0.5 g/L, which was much lower than the dosage of traditional antibiotics and macromolecular chitosan antibacterial materials. Therefore, the obtained PO not only has good functional properties, but also the raw material is green and non-toxic, inexpensive, and easy to obtain, which is a potential biomedical material.