The invention relates to a sensor chip and a manufacturing method thereof, and belongs to the technical field of designing and manufacturing of surface plasma resonance sensor chips. The chip adopts a composite structure formed by a glass substrate, a metallic film, a self-assembly film, and a metallic oxide and polymer composite thin film, in sequential arrangement from bottom to top; and nanometer metallic oxide is successfully fixed to the surface of the sensor chip by a polymer embedding method, so that the detection range of objective gas is effectively enlarged, and the sensitivity of the objective gas is effectively improved. The method disclosed by the invention is simple, the manufactured sensor chip has high sensitivity on sulphur dioxide, detection requirements under room temperature condition are met, and the sensor chip has favorable response signals within 5 ppm-40 ppm.