A new type of methane sensor was proposed which was based on micro-ring resonator. The sensor is coated cryptophane A on micro-ring surface to increase effective refractive index of the micro-ring, so as to make resonance wave length in the micro-ring resonator drift towards the right along with methane concentration increasing. Methane concentration is gotten by measuring the outputted resonance wave length. The theoretical analysis results show that change of the outputted resonance wave length of the sensor is within a free spectral range, and methane concentration measuring range is 0~15%. By comparing measurement results of SOI material and polymer material, single sensitive film and three sensitive films, a conclusion is gotten that polymeric material micro-ring with three sensitive films has larger variation width of resonance wave length, which has measurement sensitivity of 60 pm.