The present invention discloses a method of preparing graphene-rubber composites. The composite is prepared by mixing graphene powder, water and N-Methyl pyrollidone into a graphene dispersion. The dispersion is agitated with ultrasonic waves. Rubber is mixed to the dispersion until a homogenous composite is obtained. The composite is added with emulsifier and dry casted. The rubber composite has reasonable tensile strength and flexibility expected of a rubber film. The rubber composite is adapted to be used as a flexible film that can be used on a flexible surface, such as hand, to measure pressure.