This paper introduces the new type of CO2 sensor by combining optical mechanic andeletronic devices. Based on I,ambert-Beer law and using a high-quality IR detector, the gage can detectcarbon dioxide with high precision and efficiency. The detection of carbon dioxide involves some keytechniques such as current stabilization of the IR source and structure, small volume, light weight, lowpower consumption and high reliability. Meanwhile, it can be applied into many associated fields.