Abstract: Ammonia low-temperature plasma was used to modify Poly (D，L-lactide) (PLA) film and the surface characteristics after modification were studied. The results showed that plasma treatment would etch film surface，which would affect the roughness of film surface and the density of grafted ammonia group. The hydrophilicity of the modified film was increased. Its contact angle was decreased obviously from 90° to 24° and could keep stable when it was preserved at a low temperature (－20℃). The cell affinity of PLA was improved by plasma treatment.