The invention discloses a nano polymer film for surface modification of a biological material and a preparation method of the nano polymer film. The nano polymer film is prepared from polyimide, polylysine, nano titanium carbide, nano barium titanate, polydimethylsiloxane, a titanate coupling agent and aluminum oxide sol. Polyimide is dissolved in ethanol, mixed liquor is formed, polylysine is added, the mixture is stirred to be completely dissolved, polydimethylsiloxane is added slowly to an ice-water bath, the mixture is subjected to a reaction, heated, stirred, mixed with nano titanium carbide and the titanate coupling agent, stirred continuously for a reaction, subjected to ultrasonic treatment, cooled and quickly stirred; nano barium titanate and aluminum oxide sol are slowly added to the mixture for a reaction, the mixture is applied to a glass plate after being cooled, the glass plate is rinsed with distilled water, dried, cooled and soaked in distilled water, and the nano polymer film is obtained after demolding and drying. The nano polymer film has high stability and strong binding force with a substrate material and can be used for fixing of various biological material molecules; the preparation method is simple and easy to implement and low in cost.