The invention relates to a resistance-type gas sensor based on a graphene, stannic oxide and zinc oxide composite, a preparation method and application thereof, and belongs to the technical field of gas sensors. The gas sensor is composed of a monocrystalline silicon substrate, a silicon dioxide layer, a titanium adhesion layer, interdigital platinum electrodes and a gas sensitive film covering the silicon dioxide layer and the surfaces of the interdigital platinum electrodes in sequence; the structure of the titanium adhesion layer is the same as that of the interdigital platinum electrodes, and the gas sensitive film is the graphene, stannic oxide and zinc oxide ternary composite; the ternary composite is prepared by mixing graphene, stannic oxide and zinc oxide and is of a three-dimensional porous structure. Before and after the gas sensitive film makes contact with gas to be tested, the resistance of the gas sensitive film can change, and the sensitivity of the sensor can be obtained by measuring resistance changes between the interdigital platinum electrodes. The sensor has high response sensitivity, rapid response recovery rate and good response reversibility at room temperature, and the problem that the a stannic oxide and zinc oxide gas sensor can work only at high temperature is solved.