In the present study, a new method to immobilize type I collagen on the surface of poly-l-lactic acid (PLLA) film was invented. The film treated by Sodium hydroxide was immersed alternately in 2-(N-morpholino)ethanesulfonic acid (MES) buffer containing N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS), and MES buffer containing type I collagen. Consequently, a kind of hybrid biodegradable film with a transition from PLLA to crosslinked collagen was synthesized. Laser scanning confocal microscopy (LSCM) was used to investigate the treated films. Grafting of proteins on the PLLA surface was observed. The result was further confirmed using X-ray photoelectron spectroscopy (XPS).